Nadir Kraken

The whole payoff sits in an optional tax you attach to every draw: each card you see offers the chance to spend one more mana, and each yes grows the Kraken by a counter and drops a Tentacle beside it. That makes it a rare threat that scales off the same resource it competes for. Because the trigger keys off any card drawn, not just the per-turn draw step, it stacks with cantrip chains in a single turn and even fires on opponents' turns when you draw at instant speed, so a well-timed draw spell can spawn a body mid-combat. Blue draw engines are built to pull ahead on cards; this one converts that surplus into a board, folding card advantage and clock onto one axis instead of leaving them at odds. The optional payment is what keeps it fair without ever stranding the effect: the trigger always goes on the stack, but paying is a choice, so a Kraken drawn behind on tempo can sit as a 2/3 and decline every payment while one drawn with mana to burn spirals into a growing mob. It resolves an old problem for draw-heavy blue, which historically piled up cards and had nothing to do with the excess but discard to hand size. Here each spare card and each spare mana buy a body. The counter and the token are two rewards from one payment, so it threatens a lone large attacker and a swarm at once, and never keeps all its value where a single removal spell can hit.