I noticed two bugs plaing against the computer with Lord Erebus.
EDIT: NEW BUG
1. The night crawlers stop spawning. I dont know what originally triggered this as at the start of the game they were spawning fine and then just stopped at around lvl 8 (at the time i had no night crawlers), about lvl 12 i got the skill that increases the number of night crawlers you can have and they started spawning again. I have had this issue in two seperate games...
2. Lord Erebus stops moving/attacking, it happens after using a skill he just stands there until you deselect him then select him again and issue a command.
3. The bite skill not working sometimes, when pressing one the cross icon comes but when I click on the target nothing happens...
Also against the computer playing regulus on Nightmare lvl he seems very OP once you are reaching lvl 15-20 and have all your minions i was killing regulus in 10-20 seconds whilst remaing at full health due to life steal kills.
He is very fun to play so hope this helps...