Aether Vial

As this artifact enters, choose an opponent. At the beginning of the chosen player's upkeep, this artifact deals X damage to that player, where X is the number of cards in their hand minus 4.

Imprint — When this artifact enters, you may exile an instant card with mana value 2 or less from your hand. 2, T: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

At the beginning of your upkeep, you gain X life, where X is the number of cards in your hand minus 4.

2, T, Sacrifice this artifact: Search target player's library for three cards and exile them. Then that player shuffles.

Whenever Karn blocks or becomes blocked, it gets -4/+4 until end of turn. 1: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn.

At the beginning of your upkeep, sacrifice this creature unless you discard a card. 2: This creature deals 1 damage to target creature. 2: Regenerate this creature.

T, Sacrifice this artifact: Each player exiles all cards from their hand face down and draws seven cards. At the beginning of the next end step, each player discards their hand and returns to their hand each card they exiled this way.

Whenever you cast an instant or sorcery spell, you may pay 3. If you do, copy that spell. You may choose new targets for the copy.