Harrowing Swarm

When you unlock this door, this Room deals 2 damage to target creature.

When Ethrimik enters, manifest dread. Other creatures you control get +1/+1. As long as you control another creature, Ethrimik can't attack or block.

Survival — At the beginning of your second main phase, if Improvising Aerialist is tapped, Improvising Aerialist and the top creature card in your library without flying perpetually gain flying.

Enchantment spells you cast have convoke. Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, conjure a card named Mothlight Processionist into your hand. Discard that card at the beginning of the next end step.

Creatures you control get +1/+0.

Exile target creature. The exiled card perpetually becomes an enchantment. At the beginning of your next end step, put it onto the battlefield under your control. (It loses all other card types.)

Impending 3—2UU Whenever Lurker in the Deep enters or attacks, seek a nonland card. Whenever you seek one or more cards during your turn, conjure a duplicate of each of those cards into your hand, then manifest those duplicates.

Enchantment creatures you control have menace. Whenever one or more enchantment creatures you control deal combat damage to a player, exile a random creature card from that player's library. Create a token that's a copy of that card, except it's a 1/1 enchantment creature.