Wing Shards

Wing Shards doesn’t target the creature to be sacrificed. The target player chooses the creature as it resolves.

An “attacking creature” is one that has been declared as an attacker or put onto the battlefield attacking during a turn’s combat. Unless that creature leaves combat, it continues to be an attacking creature through the end of combat step, even if the player it was attacking has left the game or the planeswalker it was attacking has left combat.