Here is the Tips for Assault's Khimera

1. Kill the goblin "without" engage the Khimera
2. after Kill goblin, no matter what do not engage Khimera, this Assault's Khimera will start with flag wing up but it's can break wing easily with just some critical move (I break it with club on blue) and once you break wing in this fight. It will not flag wing up again. So if you already broke it's wing just kill it. (Form my test, even I hold it til almost time up it's never wing up again.)
3 So, After defeat goblin just turn and use Bludgeon or any "Non Critical Spell" on it for provide it TP. If nothing wrong you will see it for sure, since I already learned it form this Assault.