Now I'm calculating the size of the enemy "army" at level 50 on Impossible difficulty.
The number of Cerberuses is somewhere between 1500 and 4500. But that's only if there's nothing else. Honestly, I can hardly imagine an enemy army consisting of just one stack of 4500 Cerberuses... But if that's the case, then first a few casts of Soul Drain, if it hasn't been removed.
1) Only in one stack. Just one, Lizard! The other stacks are just as numerous, no exaggeration. And there are many of them.
2) It wasn't Impossible difficulty. Either Normal or Hard.
3) And such armies filled the entire location. Whew, I ran around a lot.