Invisible Collissions

Rules Questions

Dark Archive

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Okay, so I see a bad guy, and I run up to him to attack. However, there is another bad guy, invisible, between me and my target. What happens when I enter the square occupied by the invisible bad guy?

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Overrun attempt vs. an invisible opponent?

The Exchange

Attacks of Opportunity, usually.

You can't move through anyone but friendlies, so the attempt to move into the invisible guy's square fails. As a DM I would stop the player mid-movement and let them decide what to do from there. They can continue their movement by going around, for instance. They may have a standard action left, which would allow them to attack or cast a spell, or other actions.

Basically I treat it exactly like a square of difficult terrain that a player didn't notice. "Hey, Bob, right there... difficult terrain." Bob then re-designs his actions from that point forward.

cp wrote:
Attacks of Opportunity, usually.

If the bad guy can't perceive you, he can't take an aoo.

The Exchange

OP never said he was invisible-and it was meant more humorously than seriously.

If the invisible guy was trying to stay invisible, he could let you pass through the square and not touch you at all, allowing you to move through the square. Though I would put a 50% chance of running into him.

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technically you can move through opponents squares with a successful acrobatics roll. i would force an acrobatics check, if he succeeds he gets to pass through, but up to the GM if he notices anything (i would argue he would notice brushing up against something). if he fails his movement ends but provokes an aoo from the invisible guy. i would give the invisible guy the option to have the character automatically succeed the acrobatics check to get by if he wishes.

i think this is as close as you can get to RAW, but someone correct me if i missed something. obviously there is some gm fiat in there too but i tried to get as close as possible to RAW.

As I see it, the difference between moving through an allies square and an enemies is that the ally wants you to have free movement a.d gets out of your way, while the enemy isn't about to do you any favours.

So in this scenario, two things can happen.

1) The enemy wants to remain undetected and gets out of your way.

2) He wants to bring the smack down so he takes the AoO while you're flat footed.

Does the charging character realize he bumped into something/someone?

Gwen Smith wrote:
Does the charging character realize he bumped into something/someone?

i think that is really up to the GM, there are no rules written that handle that sort of situation.

personally i would say there is some sort of % chance of noticing if the invisible character chooses to let you through their square with the intention of the charging character not noticing them. or maybe a reflex save of some kind by the invisible character? DC based on how many squares the charging character moved before reaching your square, the farther away they started the easier the DC will be, since you had time to see them coming. this is all just me making up stuff that sounds reasonable in my head :)

We just dealt with this in the last session I ran. The Sorcerer was invisible and an ogre moved through his square to attack the paladin. We ruled that if you are invisible and something attempts to move through your square you can just choose to avoid it. If there is nowhere to move you can attempt an acrobatics to avoid collision. If you fail to avoid or choose not to move the creature bumps into you and realizes you are there, it can then stop and attack you with all relevant modifiers for being invisible.

Liberty's Edge

Pathfinder Battles Case Subscriber

I always just use the Overrun rules as a guide. No actual Overrun is taking place so no CMB roll is made but, because it's a similar situation, I stick to the rule that a creature you are trying to overrun can simply choose to move out of your way. The invisible creature does have the option to make an AoO against the person moving through its square using all the advantages that being invisible brings, but I rarely have monsters do this unless there's a clear combat advantage (levels of Rogue for instance.)

Also, unlike the rules for Overrun, I don't just make the moving character stop adjacent to the creature if the invisible creature is too large to Overrun. As long as the massive invisible creature is aware of the mover and is capable of lifting a leg or raising its tail or whatever, it can just shift its bulk to get out of the way. My only exception is with creatures that are so voluminous, they can't get easily contort their way out of the mover's path. A really big ooze or possibly an elemental are good examples. An invisible ooze, of course, welcomes any attempt by a person to move through its squares.

In those cases where a character moves through a massive invisible creature's squares, I may allow them a free Perception check to notice the creature's smell or a sudden shift of air or warmth.

Before the questions and analysis:

There are very few ways to handle moving through the squares of other creatures, and I've actually dealt with a lot of them, which has caused me to think about it quite a deal.

One way to move through a square is if a creature is friendly (and thus, allows you to). Obvious; nothing further.

Another way is if a creature is Helpless (unconscious, bound). Obvious; nothing further.

A creature that is Tiny or smaller can move into or through squares of anybody, including other Tiny creatures. This is necessary because they have no reach and otherwise would not be able to attack opponents, being unable to penetrate the 'occupied square force-field'.

After that, you can be three size categories smaller than a creature. A Small creature can walk through a Huge creature. A Medium creature can move freely through a Gargantuan creature.

You can move through a creature using Acrobatics, typically by using a Move action and succeeding a Combat Maneuver check against the CMDs of nearby creatures in turn. Moving at greater than half speed imposes a penalty; any creature you move directly through gains a very large bonus to its CMD. If you fail any of these checks, you trigger an attack of opportunity from that creature. If you are dealt damage (technically from any source) while using Acrobatics, you must make the roll a second time or fall Prone and end your movement.

Interesting fiddly rule #1: This means that you can force somebody to risk becoming prone even if they can fairly easily beat the CMD of their threatening opponents by Readying an action to deal them damage during their acrobatic stunt. This is much more effective -- the hypothetical attacker may have a much easier time hitting them and causing them to fail a kinda-easy check than they would on their own, requiring them to fail a kinda-easy check, get successfully hit by their adjacent opponent, and then fail the kinda-easy check again. That total chance can be remote at times.

Interesting fiddly rule #2: Even though flying creatures cannot be tripped, if they are damaged while attempting to move through your threatened squares, they still risk falling or becoming prone. They have immunity to being tripped -- not to becoming prone. Be wary of players (or GMs) using the Fly spell as a method of freely~ tumbling around enemies.

You can Overrun, which is a Standard action as part of movement.

On to the questions ...

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So here are three hairy questions that I often hear people ask about these rules:

Q1) What happens if I try to move through an invisible creature? [Assume Small+ character, and hostile invisible NPC]

If you only intend to move 5 feet, then you may make a 5-foot step. Your first square is not considered threatened when all you make is a 5-foot step in a round. However, a 5-foot step is not explicitly one of the actions that allows you to enter the square of a hostile creature. Many people would presume that you 'bump' into the creature and retain the ability to move elsewhere.

If you intend to move more than 5 feet, then the invisible creature may choose to make an attack any one time you leave a threatened square without trying to enter the square it occupies* (moving through several threatened squares in considered one opportunity, but the creature is not magically stopped from attacking you if it decides not to after the first square and then you dance circles around it). If a character attempted to move into a square with an invisible creature, many cases would result in the creature striking the moving character (-Dex), and the moving character's turn being interrupted to inform it that an attack has been attempted upon it from directly ahead. The character may attempt to continue the movement -- hey, the creature might have 5 foot stepped away as part of Readied action -- but if the square is still occupied, then it will be impenetrable until such time as the character attempts to Overrun the creature or Tumble through the square.

[* If you try to move from a threatened square into a creature's space using normal movement, the attempt will fail. Because attacks of opportunity trigger when you leave a square and you haven't left the square, the attack of opportunity will not trigger by RAW.]

If the character attempts to Tumble through the square, there are few special modifiers. Tumbling is not an attack. However, if an entered square is still occupied by the enemy, then the enemy's CMD is gains a bonus.

If the character attempts to Overrun the creature and does not have the Improved Overrun ability, it triggers an(other) Attack of Opportunity (if the opponent can make one), and any resulting damage penalizes the Overrun maneuver. The enemy may now allow the character to pass through. If it does not, it benefits from Total Concealment (Combat Maneuvers are attacks) and the attacker must contend with miss chance. Failure indicates that the attacker's movement is at an end. Success indicates that it can move through the square. Success by 5+ indicates successful movement and that the enemy is knocked Prone.

If for some reason the character ends his movement in the enemy's square and there is no special effect that indicates otherwise, then it is occupying an illegal square (it is not even legal to end movement in a square occupied by a non-Helpless friend -- permission does nothing). Such a creature ejects you from its square immediately (Special Movement Rules, CRB p. 194).

On to Q1, Part B ...

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Q1B) What if I'm invisible and I don't want a character to know I'm there?

There are creatures that would probably like to stay invisible and undetected yet they are not allowed to allow creatures to safely occupy the same square. A invisible squishy wizard, for example, may not care at all about gaining attacks of opportunity with his dagger -- he'd really rather give an oblivious fighter plenty of room so he can sneak away.

My best recommendation for these creatures is either a build that allows you to make a 5 foot step when an opponent triggers an attack of opportunity, or Readying actions that would trigger if somebody attempts to enter your square (also remember that you can 5 foot step in addition to a Readied action if that's all your movement for the round -- rather than simply readying a movement, you could ready an attack and then 5 foot step in some direction freely).

Barring the forethought necessary for those two things, you may be able to petition your GM for a special ruling that would allow a creature to occupy the same square as your invisible creature without knowing it is there. Remember that you would have to sacrifice your attacks of opportunity for as long as you remain undetected, as well as succeed on Stealth checks. For fairness reasons, GMs may apply a penalty to Stealth rolls for being extremely close, and if the probing character should spend a Standard action to check adjacent squares for invisible opponents, the creature should get a free (unknown) attempt on its own square if not automatically find the invisible occupier.

However, GMs be warned -- this may cause unusual questions from -both- characters regarding whether they should gain special defensive bonuses (such as Cover, or a flat 50% chance to hit the wrong creature) from occupying the same square. Questions like this may be why it's illegal in the first place, and you're automatically ejected if it happens anyway.

2) What happens if I try to Charge through an invisible creature?

Officially, "If any line from your starting space to the ending space passes through a square that blocks movement, slows movement, or contains a creature (even an ally), you can’t charge." So, RAW, if you attempt to charge an enemy and there is an invisible creature in between you, you can't perform the Charge for some reason.

Some people feel that it is unrealistic to be artificially prevented from starting the charge due to a non-apparent factor such as this, and further complain that characters could find invisible creatures by attempting charges in different directions and seeing which one fails. For this reason, many would allow you to move to the square in front of the blocking creature.

3) What happens if I am invisible and try to move through a creature?

The normal rules still apply. You can move through the creature if it is friendly, Helpless, if you are Tiny or smaller, if you are three or more size categories smaller than the creature, or if you Tumble or Overrun the creature.

If you Overrun against the creature, it typically cannot perform Attacks of Opportunity against you because you benefit from Full Concealment, so you do not risk being damaged or having your roll penalized. Officially, it retains the right to avoid you (which it may prefer to do, so there's no risk it is knocked Prone. Some DMs think they cannot avoid you, but that is a house-rule). You may make your Combat Maneuver check against its CMD -- because penalties that apply to AC also apply to CMD, and an Overrun is still an attack, the target's CMD should not include a positive Dex modifier or Dodge bonuses unless it has Uncanny Dodge due to your catching it unaware.

If you have the ability to Tumble (your speed is not penalized due to armor or load), then you should almost always Tumble instead. The failure of a Tumble check is that a creature can make an Attack of Opportunity on you -- however, because you are benefitting from full concealment, creatures cannot perform AoOs on you. This means that when you are invisible, there is usually no disadvantage or risk to tumbling through a creature's occupied square at full speed.

End analysis.

Also, Overrun is an attack, and would technically end your Invisibility.

The Exchange

So, presuming person acting is not invisible and opponent B is invisible and oppenent C is visible.

If A moved to attack C, I would rule that he is not allowed to enter A's square; I would then proceed to the section of the rules where locating an invisible opponents are.

If A charged, I would rule the charge was interrupted, at the square before B. A is left with either a single attack at B, a single attack at C with a reach weapon. I would confer the benefits of a charge if he attacked C, and the penalties (only) if he attacked B.

Even if B wished to remain undetected, I think those actions take more than is allowed under the rules - and make it essentially impossible for invisible people to be located a large % of the time. Now, if B readied an action to move out of the way.. All is fine. His actions would trip and A would proceed without difficulty to C.

Dark Archive

I think I'm more confused now than I was before I asked... :)

Based on the above, it would seem what happens when a visible character attempts to move through a square occupied by an invisible character varies by the type or purpose of the movement.

I've likely missed or misunderstood something, but here it goes...

5-foot step: If the square is occupied, just doesn't happen. The moving character knows the square is occupied, and no AoO is provoked.

Just moving/move action: The movement provokes an AoO from the invisible character, but the invisible character need not take advantage and in fact can opt to allow the moving through his square as if he were an ally. If the AoO is taken, the moving character may end or continue his movement. If the AoO is not taken and the invisible character allows him through the square, there may or may not be a chance (say 50% due to the invisible character's total concealment) for the moving character to realize he moved through an occupied square. If the invisible character does not take the AoO, but also does not allow the moving character through his square (acting as an enemy), movement doesn't end and may continue through other squares, but the moving character knows the square is occupied. In this case the moving character may using other methods to move through the occupied square, such as Acrobatics.

Charging at some other target which requires moving through the square occupied by the invisible creature: Movement ends, and the entire action may be over/foiled, or the charge may be converted into a charge or overrun into the invisible character.


Well since you can't move through an enemies square you stop at the square just ahead of him and probably provoke an AoO (anyone have an actual rule for this. All I have is the acrobatics text). If the enemy is smart they don't take it, if their dumb they do and break invisibility.

This exact thing is called a poor mans see invisibility. Take the guy with the most movement and have him move through each square until you find one you can't get into. Now the rest of the party knows the square and can attack at a 50% miss chance.

Eben TheQuiet wrote:
Overrun attempt vs. an invisible opponent?

This is the way I've always handled it in the past. One thing I don't like about this is you are dictating the characters action. The second is it messy when the character has already taken a standard action.

I'm thinking of playing like this:
Invisible defender can elect to simply let you pass (per the rules on overrun).
Invisible defender gets AoO for you leaving your square (per normal AoO rules).
You return to your last legal square (per the rules on ending movement in an illegal square) and you may elect to go around, overrun, bull rush, attack, as you desire and your remaining actions allow (per normal combat rules).

EDIT: added rules reasoning.

Well, this came up today.

I was running a few one-shot battles so a player could test how a build worked out, and I decided one of them was a paranoid Efreet with a room of dummy images to distract attackers.

So the character walks into the throne room and begins combat with the Permanent Images, emerging victorious but alerting an Efreet in the next room.

PC Stealths and begins creeping along a wall, hiding behind tapestries.

Efreet buffs a bit, including an Invisibility and stealthily walks into a doorway.

PC turns corner and, having already spend movement, attempts to enter and then end turn in the doorway so he can explore the room with full movement next round.

Discussion ended up getting kinda huge. We discussed:

* The possibility that the character would just 'bump' and be denied movement, which was judged suboptimal because it means you could just walk around a room until you bump into a square as a cheap method of detecting invisibility
* The possibility that if one character were aware of the other, that character could choose to allow the other creature to occupy the same space. But inconsistent with the rules that don't even let friendly creatures share spaces with you.
* The possibility that you could just 'miss' a character when trying to enter their square, meaning 50% chance one accidentally bumped the other and they became aware of each other
* Criticism of a CMB versus CMD-style situation, since a DM may not want to tell a player "your character doesn't know he's ending in a space occupied by an enemy which would love it if he ended it there so he could full attack, but one of us needs to roll to see if you touch me, or I successfully avoid you, or what"
* Discussion about whether the creature being moved on could make some kind of Reflex save to 5 foot step to the next square. Pointing out that in our particular example, both creatures were unaware. Pointing out that creatures can make Reflex saves even when unaware (Fireball). Pointing out that it doesn't make sense for a creature to make a saving throw and move away unless it has detected something.
* Argument over whether the Efreet (Huge at the time) would have penalties hitting the PC once he became aware of it. Analogies were made toward halflings having no penalties to hitting cats in their own square.
* Perusing the rules to see if applying Squeezing conditions to both creatures was appropriate.
And more, not necessarily in that order.

A very meandering argument about can you do this, if so then how, do I get a check to notice or prevent that, what if we're both unaware, what if somebody is aware but want to let it happen, is it really important not to end occupying another creature's space, what happens if you do, blahblahblah.

The headache of the extended discussion makes me wonder if that's why they said "You can only enter in these conditions : If you end your turn in their space, you are always shunted out."

Another disadvantage: Possibly having two minis on the same square. I already dislike 3-D combats in part because flying creatures end up directly above another creature too often.

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