The other night a couple friends and I were playing a three man game against the new Gloomweaver. One of our heros was Haka and he hit a Savage Mana early. Since this was our first game against the new Gloom and we hadn't read his back too carefully we started intentionally feeding Savage Mana.
We broke the game when every single villain card was either under Savage Mana, in play, or a copy of Vast Following. The next time Gloomy had to draw a card it was just going to just be an infinite cycle of Vast Followings doing nothing. We decided to just put them all in the trash and continue on knowing that eventually there would be other cards in the trash.
Well eventually we flipped Gloomy and Haka (who had gotten 3 copies of dominion early giving him massive card draw) played a Haka of Battle where he discarded 33 cards (his deck and trash were both empty) and then used Savage Mana with 18 cards under it for a total of 69 damage in one shot.
The hilarious thing to our group is that Haka does toxic damage with Savage Mana so our group has always joked that he eats enemies and then either vomits or craps them out when he used the power. Well the back side of the Gloomy shows him eating his followers and mechnically he kills his own cultists to play cards. So basically Haka beat Gloomweaver at his own game!