Idea for counterspelling rules

[jeffhartsell]

Currently counterspelling is typically seen as a waste of time. So, since AoOs are seldom used by spellcasters, I was thinking that counterspells should be a form of AoO against spells.

Rules:
Any spellcaster can expend a spell of equal or greater spell level to attempt an AoO dispel check to counter a spell being cast. The dispel check is 1d20 +1 per caster level (see maximum below) + level difference in spells against a DC of 11 + the spell’s caster level.

If a 4th-level or lower spell is expended to counter, the maximum caster level for the dispel check is 10, if the spell is fifth or higher there is no maximum.

Spell Reflexes [Metamagic]
Benefit: The character may make a number of additional attacks of opportunity dispel checks equal to the character's Dexterity modifier. The character still may only make one attack of opportunity dispel per enemy. The character may also make attacks of opportunity dispels while flat-footed.

 

[Michael Morris]

Counterspelling is not the primary application of dispel magic. It's one of three functions. The Dusk setting features dedicated counterspells of varying degrees of power. Here are a few.

Counterspell
Dissipate
Power Sink
Quash
Refutation

 

[Spatzimaus]

There's also a few Feats in the splatbooks that help here. Reactive Counterspell? Don't have the books in front of me, but I think it lets you counter a spell immediately if you spend the action next turn.

Having counterspells be AoOs (and therefore not take any time to cast) would be a bit much. Besides, then you get into the bad situation of taking AoOs on someone you don't threaten. Making it be a caster level check is a nice balance point, and it might be okay then, but I'd definitely make it be a Feat, not a general rule change, and I'd still have a problem taking an AoO on someone you don't threaten.

Also, nitpick: your Spell Reflexes feat wouldn't be [Metamagic], since it doesn't modify a spell slot. There's also the question of whether it'd stack with Combat Reflexes or not. Since you explicitly stated "AoO dispel check" above, that'd mean Combat Reflexes would work for it too. Just get rid of Spell Reflexes, I'd say.

Your metamagic tag made me think of something, though; a Feat we came up with way back when, before the splatbooks:

REACTIVE SPELL [Metamagic]
You may use the Reactive spell to counter a similar spell as a Free Action. This counts against the limit of one quickened spell per turn. However, you may still cast the spell as a normal action if you choose.
This uses a spell slot two levels higher.

It just gains the added bonus of being a readied counterspell. Like Quicken Spell, Sorcerers can't use it unless you get around that metamagic rule. Dispel Magic becomes MUCH nastier with this Feat. We never really finished balancing this Feat since with Reactive Counterspell and Haste there wasn't as much need.