Hazoret's Favor
The whole engine turns on a trade nobody usually wants to make. Once per turn, at the start of your combat, you can push a creature you control for +2/+0 and haste, but accepting the boost stamps a delayed sacrifice on it that fires at the beginning of the very next end step: not a moment you choose, a fuse that lights the instant you say yes. Pump-and-haste is an old idea, and most of the lineage charges full price for a one-shot boost while letting you keep the body afterward; this hands you the haste for free and then takes the creature back on a fixed timer, that same turn. The inversion is the point. A midrange shell that wants its attackers to survive combat gets nothing here. It sings in a shell already planning to lose its creatures, where a hasted attacker dying on schedule is fuel rather than loss. Death triggers, aristocrat payoffs, and graveyard-recursion engines all want reliable, repeatable creature death, and this supplies a scheduled dose of it with an offensive premium attached: the +2/+0 lets a token push real damage on its way out, the haste lets a freshly cast creature swing immediately before it gets fed to the yard. Read as a beatdown enchantment, it looks like a downside wearing an upside as a disguise. Read as an aristocrats accessory that happens to swing for extra, the forced sacrifice stops being a cost and becomes the reason to run it.
