Yosyer, the Certainty

Haste, Hexproof
On each player's upkeep, that player reveals the top three cards of their library. They may cast them without paying their mana costs. If they do, they skip their next turn.
{5},{t}: Target player gains an extra turn. On the beginning of their upkeep, they lose X life where X is how many spells they cast on their last turn.