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Every 50th kill of this enemy drops Gingerbread Man Banner.when you run into him
He belongs to the Frost Moon and nothing else. No item summons one and no ordinary winter night produces one, so meeting him means you started the event, which itself needs Hardmode and a dead Plantera.
fighting him
He walks at you and that is the whole of it. His movement copies the Splinterling, so the read is the same: ground level, no ranged attack, nothing that changes as he takes damage. In a Frost Moon arena he is padding between the things that can actually kill you, and the real danger is a wall of them shoving you off a platform rather than any single swing.
why you still clear him
He leaves nothing behind: no coins, no loot, only the banner after enough kills. What he does hand over is wave progress, and the harder your difficulty the more each one counts toward the later waves where the good drops live. Letting a crowd pile up stalls the event, so bring something that pierces and sweep them off the ground in one pass.
His death gores show a frowning face, which is the one detail anybody remembers about him.