Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Counterspell

Araumi of the Dead Tide

{T}, Exile cards from your graveyard equal to the number of opponents you have: Target creature card in your graveyard gains encore until end of turn. The encore cost is equal to its mana cost. (Exile the creature card and pay its mana cost: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Shriekmaw

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
When Shriekmaw enters, destroy target nonartifact, nonblack creature.
Evoke {1}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Stitcher's Supplier

When Stitcher's Supplier enters or dies, mill three cards. (Put the top three cards of your library into your graveyard.)