Have

Dress Down

Flash
When Dress Down enters, draw a card.
Creatures lose all abilities.
At the beginning of the end step, sacrifice Dress Down.

Mystic Remora

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Glaciers

At the beginning of your upkeep, sacrifice Glaciers unless you pay {W}{U}.
All Mountains are Plains.

Seal of Cleansing

Sacrifice Seal of Cleansing: Destroy target artifact or enchantment.

Standstill

When a player casts a spell, sacrifice Standstill. If you do, each of that player's opponents draws three cards.

The Master of Keys

Flying
When The Master of Keys enters, put X +1/+1 counters on it and mill twice X cards.
Each enchantment card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.)

Seal of Removal

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Doom Foretold

At the beginning of each player's upkeep, that player sacrifices a nonland, nontoken permanent of their choice. If that player can't, they discard a card, they lose 2 life, you draw a card, you gain 2 life, you create a 2/2 white Knight creature token with vigilance, then you sacrifice Doom Foretold.