Shu Yun, the Silent Tempest

Most prowess creatures convert spell velocity into a single damage axis: cast more, swing bigger. This one splits the same trigger into two outputs at once. Every noncreature spell pumps the body the standard +1/+1, but it also fires a second triggered ability with an optional cost: pay two hybrid Boros mana and any target creature gains double strike for the turn. Blue is the only color in the casting cost, yet the payment quietly pulls the card toward the three-color wedge it was built to anchor; the mono-blue chassis keeps it castable in a control or tempo shell while the payment pledges you to a wider manabase. The doubling is where the math turns lethal: point it at the monk itself after a couple of cheap spells and a 3/2 becomes a threat dealing its inflated power twice. Aim it at another attacker you control and a draw-go shell suddenly has a finisher stapled to its plan. Because the trigger keys off casting rather than tapping, it can resolve several times a turn, but each instance demands both a fresh noncreature spell and the mana to pay for it, so the ceiling is bounded by how much of the turn you commit to offense rather than answers. It is a build-around that asks for a deck full of cheap instants and sorceries and then rewards that deck with a clock those spells alone could never produce.