Make sure to go for him before you save Halsin, if you are too far at the grove quest line he will be dead.
I am not sure if he is going to there if you side with goblins, let me know if you do

If you have Sazza with you, kill the goblins and heal Findal, he would have a problem with Sazza and you will have to make checks to convince him to let her go, otherwise he will stupidly attack you. So the best way is escort Sazza out first, then return and heal Findal.

If you heal Findal before you killed the goblins, he will joing the battle, but he honestly sucks, so I would recommend leave him out of it.

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