Incapacitation

[Griss]

Both of Ifrit's horn is breakable, i believe brekaing right one will render it unable to regen hp, we used it before for 4man ifrit attempt.

Here is full list of incap.
http://lodestone.finalfantasyxiv.com.../battle02.html

Yep and op before you start trying to spam skull sunder or spirits within to break his horns. They are classified under the Other (right) and Other (left). You will only be able to break the right horn, and will need to have a lance or bow user beak the other.