Those [...] require very specific and in come cases bizarre decks to defeat
Bizarre might be the right word in this case.
Slow... Yeah, that is a bit of an issue. I'm mostly between 300-400 seconds, though I'm not playing too fast. Summoning a nymph queen to turn all of the entropy pillars into nymphs speeds the game up a bit in the end and is sometimes even needed when BE comes in late.
I've played a few more games (another 6 wins and 5 loses with one of those caused by me acting dumb), which adds up to 20 games, 12 wins, 8 loses and 5 EMs.
@Blazing Moonwalker: How do you actually plan to get your BE creatures killed? You can only use it on Flayers (Well, and Nymph Queens) and Chaos Lord will target your nymphs over them. + every mutant has a maximum of 1 turn to use his ability.