Basilica Stalker

The disguise cost is the whole design conversation here. Cast face up, this is a six-mana 3/4 flier that trickles you a life and a surveil each time it connects: a serviceable body attached to a slow attrition engine, but nobody was going to pay six for that on rate alone. The disguise mode reframes it. Down for three as a 2/2 with ward 2, it lands early, dodges cheap removal, and holds up as a threat whose eventual flip is telegraphed but not answerable at a discount. What makes the flip interesting is the timing: you can turn it face up any time, so a blocker declared against a nondescript 2/2 can meet a 3/4 flier mid-combat, and the ward tax on the face-down side buys the time to get there. That combat-damage trigger also does more than gain life. Surveil is graveyard-building disguised as card selection, so a Vampire that keeps connecting is quietly stocking a yard for whatever else the black deck wants to do with it. The Detective typing and the surveil rider are of a piece with the investigation-flavored design language this creature comes from, where card-manipulation and evidence-gathering share a mechanical vocabulary. On its own it is a midrange grinder; the reason it earns its slot is that disguise lets it play two different games depending on when the mana shows up.