First Appearance: Sentinels of the Multiverse: Infernal Relics
Who he is: The living nightmare of the Multiverse
Initial Side: Nightmare Walker
Innate Power (Initial Side): At the start of the villain turn, if there are 3 villain relics in the villain trash, the heroes win. Whenever a cultist is destroyed, search the villain trash for a zombie card and put it into play.
Advanced Power (Initial Side): GloomWeaver is immune to melee and projectile damage.
Villain Cards that Begin Game in Play: (H)—where H is equal to the number of heroes—zombie cards.
How he flips to his other side: When there are three villain relics in play.
Nemesis: NightMist
Second Side: Demon-God Incarnate

Innate Power (Second Side): When flipped to this side, GloomWeaver regains (H) times 10 HP. Whenever a cultist is destroyed, search the villain trash for a zombie card and put it into play. At the end of the villain turn, GloomWeaver deals X toxic damage to the (H) minus 1 hero targets with the highest HP, where X = the number of voodoo pins in play plus 2.
Advanced Power (Second Side): At the end of the villain turn, GloomWeaver deals (H) infernal damage to the hero target with the lowest HP.

Most Fiendish Ongoing Card: Strength of the Grave: Increase damage dealt by zombies by X, where X = the number of zombies in play. Reduce damage dealt to zombies by 1.
Most Fiendish One-Shot Card: Vast Following: Shuffle the villain trash and reveal the top (H) cards. Put any revealed cultists and relics into play. Put the other revealed cards back in the trash. Play the top card of the villain deck.
Most Fiendish Villain Target Card: Pouch of Bones (25 HP): Reduce damage dealt to zombies by 1. Whenever a zombie enters play, each villain target regains (H) HP.

How to Defeat GloomWeaver: You may have read the alternate way for the heroes to win—have all three relics in the villain trash—and think that you may want to try and win that way. It’s not that easy. First, all relics have 25HP apiece, so they don’t go down easily. Second, they have nasty abilities that force your attention elsewhere. Finally, Vast Following can get relics out of the villain trash which dashes your hopes of winning. Even with all those obstacles I’ve still won this way, but I held my breath when Vast Following came into play the turn before I was going for the final blow.

You’ll probably want to win the traditional way: take out GloomWeaver himself. To do this, you won’t want any zombies in play. They don’t have too much HP, so it’s not difficult to take them out, but a lot of the other cards play off of how many zombies are in play. Voodoo pins aren’t any fun either. They can cramp a hero’s style, but a lot of these aren’t so bad and some heroes can soak up damage from the ones that deal damage. I’d get rid of Indigo Pin though. This nasty pin discards a card from your hand at random.

The cultists are more annoying than anything else. Perhaps Chosen Disciple is the most problematic. She deals damage based on how many zombies are in play and she feeds her ability by flooding the field with zombies. Pouch of Bones gets the nod for most fiendish villain target because of its high HP, ability to make zombies even more annoying (and cultists because you may not want to destroy them and bring a zombie back into play), and the fact that its ability is the only one heroes can’t negate by discarding.

Ultimately, you’ll have to prioritize which cards to take out first. Not all of these will be out in play at once, but I’d start with Indigo Pin, Chosen Disciple, Zombies, Pouch of Bones, and then any other target that’s dealing you damage you can’t or don’t want to soak before taking on the big man himself. And if you have an opening for winning by taking out all three relics, go for it.