Good boss killer skill for witch minion, early game

As the title states.. I'm trying to kinda put together my "own" build. I have a lot hrs on this game but still need to learn alot more. But I'm lvl 25 witch, not ascended, minion/fire (firewall), with unearth and bone cage.

Im doing pretty damn good with normal enimies and mowing through them pretty fast. But the bosses take me awhile. Iv played this alot so I know the bosses and still get em but they take me a good chunk of time.. I also have focused heavy on minion nodes in the tree. Pretty much only those.

I also use grim feast which idk how much that helps me and pain offering which seems to help.. But I'm I not sure if I'm using the right supports or should I be using a diff skill to help me take out the bosses. Iv played enough to where I have currency to rebuild or change stuff up

I'm at work but I can post my poe ninja later.