Abyssal Gatekeeper

The whole card is the death trigger, and the trigger is built to be symmetrical: when this dies, the controller and every opponent each sacrifice a creature of their choice. That symmetry is what makes the body a delivery mechanism rather than a stat line. As a chump-blocker, it walks into combat and drags a creature down with it; against a board where you hold expendable fodder and your opponent holds only their best, that exchange trades your throwaway for their premium threat. The complication is that the edict taxes you as well, so the card wants a deck stocked with tokens or other throwaway bodies you do not mind feeding into your own clause. Structurally it is a creature-shaped version of the forced sacrifice that later sorceries like Diabolic Edict and Chainer's Edict would sharpen: because no creature is targeted, it slips past hexproof and protection that one-sided removal cannot. Bolt it to a sacrifice outlet and the wait-to-die liability disappears entirely, converting a fragile 1/1 into an on-demand valve that strips an opponent's lone blocker the moment you want the opening. The Horror is incidental; the death clause is the design, and it is untargeted attrition of the sort black has leaned on ever since.