War Screecher

The six-mana price tag on the anthem activation is the whole design: this is a mana sink for the late game, not an engine that snowballs from the early turns. It pays for a repeatable board-wide pump by making each use cost more than a full turn's worth of mana, so the ability sits inert until a go-wide deck has emptied its hand and needs somewhere to dump flooded lands. The 1/3 flying body earns its keep in the meantime, absorbing early ground attacks and chipping in over the top while tokens or small creatures fill the battlefield. When the game grinds into a standstill, a single tapped activation gives every other creature a point in both directions, and the more bodies already down, the harder that one swing lands. That deliberate expense is what keeps it a supporting common rather than a curve-topper: it never demands a deck built around it, and it never wins on its own. On an empty board it is just a 1/3 flyer with an ability too expensive to matter, which is exactly the point. It asks nothing of you until the turn you have nothing better to do with your mana, and it rewards the wide board you already committed rather than promising one.