Sphinx Sovereign

The whole engine hinges on a single word in the trigger: untapped. Leave the Sphinx home and the meter pays you three life each turn, a slow cushion that does nothing to close a game. Tap it (most naturally by attacking with the 6/6 in the air) and the trigger flips at your end step: each opponent loses three instead. That is a deliberate inversion of the usual lifegain-flyer template, where swinging and gaining life sit on the same axis. Here the two outcomes are mutually exclusive on any given turn, and the card asks a question every end step about which posture is worth more: the defensive life buffer of a creature held back, or the offensive drain that only fires while it is committed to the attack. The eight-mana three-color cost (white, double blue, black) plants it firmly in a controlling shell, where a hard-to-kill flier that grinds a life total in either stance is the kind of inevitability that wants to sit behind countermagic and removal. As an artifact creature it also bends to colorless tutors and reanimation effects that a plain Sphinx would miss. The drain is real but exposed: the trigger checks tapped status only at your end step, so any removal spell resolved before then erases the payoff entirely, and an opponent's untap tricks during their own turn are irrelevant since the Sphinx straightens up on your untap step regardless.