Tolarian Kraken

The tap-or-untap trigger is what tells you this creature is an engine piece rather than a beater: it hangs a repeatable combat and mana lever off an action a draw-heavy deck was performing anyway. Each draw offers a fresh chance to spend a single mana and either tap down an incoming attacker or untap something of yours, so the value climbs with exactly how hard the deck is churning through cards. Layer it behind wheels, loot effects, or extra draw steps, and one tap becomes a stream of them, turning a 4/6 into a defensive lock or a way to keep a mana producer or evasive threat available across turns. The design follows a familiar blue pattern of stapling a minor payoff to a routine action, but the tuning is deliberately soft: the mana tax on every trigger stops a hand full of draws from converting for free, and the effect is optional and single-target rather than a sweeping board play. What it will not do is end the game on its own. The body defends well and blocks most early threats, yet the creature is there to accumulate, not to attack. The reward is a slow, incremental grip on the board built out of incidental draws, not a burst of tempo, and a deck already flooding itself with cards is where that grip actually tightens.