Disciple of the Vault

The trigger looks modest until you do the multiplication. Each artifact put into a graveyard from the battlefield costs an opponent one life, and a 1/1 for a single black mana costs almost nothing to deploy alongside an artifact engine. The card's whole reason for existing is volume: stack two or three of them, then dump a handful of cheap artifacts into the yard in one turn and watch the loss triggers compound. That is what happened in the original artifact-block Standard, where a combo shell pairing it with Krark-Clan Ironworks (turning artifacts into mana while the Disciple turned those same artifacts into life loss) produced kill turns fast enough to earn the card a Standard ban. The design lesson is durable: a per-event life-loss trigger on a one-mana body is not priced for one event, it is priced for a board that generates dozens, and putting that trigger in an era where artifacts were the texture of every game was asking for it. The precision of the clause is what ties it permanently to combo. It does not care about nonartifact creatures dying, and it does not care about artifacts being exiled or bounced; it fires only when an artifact moves from the battlefield to the graveyard. That narrowness binds it to shells built to break the condition open in bulk rather than to any grindy sacrifice deck, and the gap between a structural exploit and incidental attrition is exactly the gap between a fair card and a banned one.