Syr Alin, the Lion's Claw

The interesting choice here is that the anthem is bolted to an attack trigger rather than a static line, and it hits every other creature you control, not just Knights. That distinction does real work. A static lord buffs the board the moment it resolves and holds it there, but the pump also evaporates the instant its source leaves; this one gives nothing until it swings, yet once the trigger resolves the +1/+1 stays put until end of turn regardless of what happens to the 4/4 afterward. That timing is the whole lever. The boost lands after attackers are declared, so it turns a merely-adequate attacking board into a lethal one and rewards committing wide the same turn you send it in, and killing the source in response to the attack no longer undoes the pump: the trigger is already on the stack, independent of the creature that made it. First strike on the body is not evasion but combat insurance: the creature handing out the buff is not the one that trades down first, so it survives the fight it starts. The cost of the design is defense and repetition. A static anthem helps you block and applies every turn just by existing; this asks you to attack to get anything at all, which is the price the card pays for stapling a mana-free team pump onto a clean, above-rate body. Where its knightly companions lean on value or resilience, this one is pure tempo: keep swinging, keep growing the team, close the door before the conditional nature of the buff has a chance to matter.