Ugin's Nexus

Extra turns are one of the oldest abuse vectors in the game, and this is the rare permanent built to switch them off at the source: while it sits on the battlefield, any extra turn a player would begin simply never happens. That alone makes it a Time Walk hatebear rendered in artifact form, but the second clause is what makes the design sing, because it flips the usual cost of committing to hate. Ordinarily a stax piece punishes the whole table, its controller included, and offers nothing back; here the controller keeps a turn in escrow. The catch is that the payoff is narrower than it looks. The extra turn comes from a replacement effect that fires only when the Nexus would be put into a graveyard from the battlefield: it never reaches the yard, since it exiles itself instead and grants the turn to whoever controls it at that moment. That last detail matters, because control and ownership can diverge: steal the artifact with a Control Magic effect, then arrange its destruction, and the thief collects the turn, not the original owner. So the piece rewards its keeper for routing it toward destruction: crack it to a sacrifice outlet, let an opponent kill it, feed it to any effect that would send it dying. Exile it, bounce it, or otherwise remove it without triggering that death, and the turn evaporates. The whole table is barred from the chained turns the Nexus outlaws, while a single instance of that same forbidden resource sits reserved for whoever can arrange its correct demise while holding the controller's seat.