Question about Tripping and Interrupting Spells

[HeIsMyPossum]

What are the rules surround tripping and spell checks? I looked through the rules but didn't find anything. For reference I am a monk using a whip for tripping purposes.

Here's a few of the situations I'm thinking could occur:

1) A spellcaster has been previously tripped, but is not grappled or pinned. If s/he doesn't stand up (to avoid AoOs), can a spell still be cast? Is there a concentration check? If so, what DC?

2)If I ready an action to trip as soon as a spell begins to be cast, and succeed, what happens to the spell? Is there a concentration check? If so, what DC?

Alternatively, is there something I should be doing that could be more advantageous than tripping? I don't have any grappling feats yet, as I am low level (level 2). I'm thinking about maybe adding dirty trick or the like. Do dirty trick maneuvers disable spell casters? Or do they just require a concentration check?

Thanks in advance!

[Oladon]

Concentration-related questions are generally answered in the Magic section of the PRD, under "Concentration". Have a look! :)

1) Being prone does not prevent the casting of spells. There's no concentration check just for being prone. Other issues which require concentration checks could still be in effect, so have a look at the Magic section.

2) There's no concentration check specifically for being tripped while casting. There are two which might potentially apply, though it'd be up to the GM: "vigorous motion" or "violent motion". (Only one would apply, of course, but it'd be up to the GM as to which, if either.)

[HeIsMyPossum]

Super Awesome Guy Named Oladon wrote:

2) There's no concentration check specifically for being tripped while casting. There are two which might potentially apply, though it'd be up to the GM: "vigorous motion" or "violent motion". (Only one would apply, of course, but it'd be up to the GM as to which, if either.)

Have you ever had to decide? I'm wondering if perhaps, to add some more variety, it would rely on my trip check. Perhaps if it hits, it counts as vigorous motion (a stumbling trip), or if I exceed their CMD by X (maybe 10? However that seems high. I'm not sure if 5 is enough though) then it's a much more effective trip that counts as "violent" motion.

Would that work? What would you suggest?

[Oladon]

HeIsMyPossum wrote:

Super Awesome Guy Named Oladon wrote:

2) There's no concentration check specifically for being tripped while casting. There are two which might potentially apply, though it'd be up to the GM: "vigorous motion" or "violent motion". (Only one would apply, of course, but it'd be up to the GM as to which, if either.)

Have you ever had to decide? I'm wondering if perhaps, to add some more variety, it would rely on my trip check. Perhaps if it hits, it counts as vigorous motion (a stumbling trip), or if I exceed their CMD by X (maybe 10? However that seems high. I'm not sure if 5 is enough though) then it's a much more effective trip that counts as "violent" motion.

Would that work? What would you suggest?

No, I haven't had to adjudicate that particular situation before... but while I was replying to your post earlier, I reached a similar solution to what you described. I think that's reasonable, just be aware that it'll be a house rule and not RAW.

[Orfamay Quest]

I'd say offhand that anything that throws you to the ground is "violent" motion. "Pitched roughly about" seems to cover tripping to me.

[HeIsMyPossum]

Orfamay Quest wrote:

I'd say offhand that anything that throws you to the ground is "violent" motion. "Pitched roughly about" seems to cover tripping to me.

That seems good I guess. If a rough wagon ride qualifies, I would guess falling to the ground would work.

I was also thinking another variation on the house rule would be something like:

DC Concentration Check = (CMB + d20 + Bonus) - CMD + 5

The first part is just the trip check. So for example:

DC Concentration Check = (5 + 15 + 3) - 15 + 5 = 13

This would make it so a "better" trip has a better chance to disrupt. Whereas a barely successful trip would only have a DC of 5 or 6. If you roll a natural 20 however, they basically have a very tiny chance to hit. Also, more powerful spellcasters would have a better chance to cast, which seems reasonable.

The other rule seems a little all or nothing. I mean casting a level one spell and needing a DC of 16 seems a little high. My character has something like a +7 to tripping (including CMB and bonuses), so I would only need their CMD - 7 to cause a very remote chance of hitting. If a character had a 15 CMD (seems common with the monsters we're running into), I would only need an 8 or better to cause a DC of 16 or higher. I'm not sure if that's fair or not.

Just an idea. Probably needs balancing though.