Baal has 3 forms
1) 10M hp
2) 50M hp
3) 250M hp

All 3 give 10K rep if you solo kill them excl bonus.
1M dam on 10M iBaal give 1000 rep.
1M dam on 50M iBaal give 200 rep.
1M dam on 250M iBaal give 40 rep.