[Mechanics] Counterspells

[Tiax]

I wanted to toss an idea out there and get your opinions on it. Counterspelling normally requires a character to be holding an action and then cast a spell to counter another spell. This has to be done simultaneously as the spell is cast.

Now, what do you think about being able to cast a spell to counter a spell that is already in effect? For example, once you know that a spell is a silent image, you can cast your silent image to prematurely end the other spell--however, you would have to roll an opposed caster level check.

The implications here are that the one who is countering is pretty much using up their action to cast a spell that only stops the other spell. This wouldn't affect a spell with an instantaneous effect, of course (no cancelling a scorching ray after it is cast, for example), but it could prematurely end the continuous damage from an acid arrow's lingering damage.

This means you can cancel enemies' ongoing spells (and makes Improved Counterspell more impressive for a feat), but that means they could do the same for you.

What do you think?

[SonofSamWich]

I think the idea is a cool one, it gives more options to choose from in combat. Do I want to dispel the acid arrow on my buddy, who might be hurting for hit points, or do I want to let them tough it out so I can cast haste on the party instead? But as a non-spell-caster class, and unlikely to pick up any levels in one, this doesn't personally affect me as much.