The Raven Man [Dominaria United Prerelease Promos] Sliver Mutant Set: Throne of Eldraine Type:

Set: Throne of Eldraine Type: Enchantment Rarity: Rare Cost: {1}{W}{B} Whenever a Knight you control attacks

This plays very similarly to the flood mechanic in the Atlantis scenario from the Atlantis and Das Buch scenario packs

you may move any number of +1/+1 counters from Forgotten Ancient onto other creatures

−9: Nicol Bolas

The Raven Man [Dominaria United Prerelease Promos] Sliver Mutant Set: Throne of Eldraine Type:Set: Dominaria United Prerelease Promos Type: Legendary Creature Human Wizard Rarity: Rare Cost: {1}{B} At the beginning of each end step, if a player discarded a card this turn, create a 1 1 black Bird creature token with flying and "This creature can't block." {3}{B}, {T}: Each opponent discards a card. Activate only as a sorcery.