Play... or Not play

At the beginning of each opponent's upkeep, that player loses X life, where X is the number of cards in that player's hand minus the number of cards in your hand.

At the beginning of each opponent's upkeep, exile all cards from your hand face down. At the beginning of your upkeep, return all cards you own exiled with this artifact to your hand, then draw a card.

Whenever an opponent casts a spell, Kaervek deals damage equal to that spell's mana value to any target.