Cast a Spell

[Rhazgul]

To cast any offensive spell (touch, distante touch, any) Do I need to roll a d20? If yes, what do I add as bonus? caster lvl? base attack? dex?

Thanks.

[Olaf the Holy]

Not normally. Stuff like fireball or slow requires no d20roll.

That said, you need to roll an attack roll if the spell requires a touch attack, melee or ranged.

In certain circumstances, mainly I'd you're threatened or attacked during casting, you need to make a concentration roll.

Concentration is d20+caster level+casting stat (intelligence for wizards, wisdom for clerics etc.)

[Rhazgul]

Yeah, but, por example, Scorching Ray? what happens here? Shocking Grasp? polar ray?

[Olaf the Holy]

It depends on what it says in the spell.

Let's look through the examples you've put forward.

1) Scorching Ray.

This says, amongst other things

Quote:

Effect: One or more rays

-blah blah blah-
... Each ray requires a ranged touch attack to hit ...
-blah blah blah-

2) Shocking Grasp

Quote:

Range: touch

Target: creature or object touched
-blah blah blah-
Your successful melee touch attack deals...
-blah blah blah-

3) Polar Ray

Quote:

Effect ray:

-blah blah blah-
...You must succeed on a ranged touch attack with the ray to deal damage to a target.
-blah blah blah-

Spells will almost always tell you what to do. Just read them through.

If you want to know more about touch attacks, ctrl+f this page for "touch".

Basically, the rules for touch attacks are this:

Melee Touch
Roll 1d20. Add Base Attack Bonus + Strength Modifier + any other modifiers that apply on melee attacks, such as Smite Evil, if you have paladin levels, or a Bard's Inspire Courage, or the -2 penalty from having the Shaken condition. The DC is the target's Touch AC.

Ranged Touch
Roll 1d20. Add Base Attack Bonus + Dexterity Modifier + any other modifiers that apply to ranged attacks, such as the penalty for shooting into melee, the bonus from Point Blank Shot, or a Bard's Inspire Courage. Unlike real ranged weapons, touch attacks from spells have no Range Increments - they hit equally well at all distances out to their maximum range. The DC is the target's Touch AC.

[412294]

Rhazgul wrote:

To cast any offensive spell (touch, distante touch, any) Do I need to roll a d20? If yes, what do I add as bonus? caster lvl? base attack? dex?

Thanks.

I'm going to go through all the possibilities.

First there is the actual casting of the spell, you usually don't need to roll anything to cast a spell, but if you take damage or are forced to cast defensively you need to make a concentration check, A concentration check is 1d20+casting stat modifier+caster level. If you cast a spell within someone's threatened area, i.e. close enough for them to melee attack you, they get to make an attack of opportunity, casting defensively is an action you take to prevent that. If you fail a concentration check you lose the spell, spending the spell slot, but nothing happens. The DC for concentration checks depends on spell level and is also based on damage taken if that's what forced you to make one.

Second case, the enemy has spell resistance, you have to make a caster level check, 1d20+caster level, the DC is their spell resistance, you beat it the spell works normally, you don't and they are unaffected by your spell.

Third case, you are using a spell that calls for a ranged touch attack, such as acid splash or scorching ray, this is a ranged attack, so 1d20+dexterity modifier+Base attack bonus, and you need to hit their touch AC to affect them.

Fourth case, the spell calls for a melee touch attack, such as shocking grasp or vampiric touch, this is a melee attack, 1d20+strength modifier+base attack bonus, and needs to hit their touch AC to affect them.

Fifth case, you need to make a touch attack and have the spellstrike class feature, you make a normal attack with your weapon and if it hits you get the spell effects as well as normal weapon effects, this is against normal AC. Don't worry about this unless you plan to play a Magus. If you do plan to play a magus there's a guide which will explain touch spells and spell strike far better than I have. http://paizo.com/threads/rzs2nler?A-Guide-to-Touch-Spells-Spellstrike-and-S pell

Sixth and final case, none of the above applies, you just cast the spell and might not need to roll at all, though you could be rolling damage, duration or other variables, the enemy also probably gets a saving throw. Unless the spell involves a caster level check you're unlikely to be rolling d20s here.

[Olaf the Holy]

That's a really good list.

[Helzminion]

This is very helpful. My biggest question was on the 3rd and 4th example and this makes sense, but I find it odd that a spellcaster still has to have a good strength/dex mod to hit with a good portion of offensive spells. I feel like it should be based more on corresponding attributes.