Firebird, Blazing Ranger

Most anthem effects run static, a flat buff that applies whether or not you commit to the red zone. This one moves the buff to the attack step and scales it off its own power, setting up a curious loop where the anthem wants to be the biggest thing swinging rather than a passive background creature. The printed 1/3 keeps the bargain honest: at a single point of power, the attack trigger hands the rest of the team +1/+0, a rounding error. Grow that flier before combat, though, and the same trigger floods every other attacker with real damage, so the whole design axis is the dependency: a flying anthem-on-attack becomes a go-wide finisher only after you have solved the problem of making its power large, and the evasion keeps it swinging where blockers are scarce so the trigger keeps firing. The "other attacking creatures" phrasing is what stops the loop from double-dipping: a pump spell or equipment still makes Firebird hit harder in combat, but that added power feeds the anthem for the rest of the board instead of stacking a second bonus onto Firebird. What emerges is a captain-of-the-charge structure that asks you to invest in one creature and cash that investment out across the whole team, living or dying on how cheaply you can push a three-drop's power upward before combat resolves.