I had about 16 lox and they got him down to about 1/3. I got him down the rest of the way with one death, but with a portal under the altar, getting back was easy, especially because I ran inside and it was the DOT that finished me off. There are some diminishing returns with lox because they get killed by AOE. So going from 16 to 20 might not make a lot of difference.

So, use the lox to soften him up but be prepared to finish the job. Wolves probably work better because they're smaller, more mouths can actually reach him at the same time without crowding each other out.