Immortus, Master of Eternity

Blue gets a mana source that pays out in proportion to how greedy its own turn has been, and the wrinkle that makes it safe is the noncreature clamp. Every point of the mana this 2/2 produces scales off cards drawn this turn, so chaining cantrips before you tap it turns a modest draw step into a ritual that funds a big X spell or a wall of counterspells. Left open, a draw-fueled faucet like this would just dump into oversized threats; restricting it to noncreature spells keeps the payout aimed at exactly the effects blue is licensed to cast, which is what lets the rate be this generous. The power-up rides a completely different axis: not mana, but a symmetric table reset that shuffles every hand and graveyard back and hands all players seven fresh cards, with a lone +1/+1 counter left behind to keep a fragile body relevant. Its cost sits high enough, and it fires only once, that it reads as a single game-shifting refuel rather than a repeatable wheel engine, discounted only if he arrived this turn. The two halves solve the same design problem from opposite directions: one ability rewards a draw-heavy shell with explosive output, the other guarantees the game keeps advancing instead of grinding to a halt behind one player's stockpiled card advantage.