I originally posted this on the wikia anonymously, but I felt I should repost here: Dark Annihilator is now (maybe since a recent patch?) vulnerable to Sloth. It kills him very fast. I started the battle under his chin (wait for him to stop moving, of course), attacking upwards and could do 20-30 damage before I had to move, the saw just goes over your head. After that you can jump in front of him attacking with both Sloth and the orbs. I'm sure you guys can come up with better strats than me for how to handle the fight. Tested on angel mode only because I'm bad at this game.

Wow this is incredible thanks for sharing this we don't visit the wiki much but we have a discord its on the side bar, incredible strat !

Glad to help :)