Sphinx Mindbreaker

Mill as a creature keyword sits in an odd corner of the design space, because it forces the card to commit to a clock that most mill strategies do not actually want: a one-time enters-the-battlefield burn of ten cards, delivered by a seven-mana body, is a slow start on a plan that lives or dies by tempo. What the design gives up in speed it partly repays in resilience. This is a 6/6 flyer that dents a library the moment it lands and keeps swinging afterward, so the mill is not the whole gameplan but a rider on a threat that already closes games in the air. That dual function is what the card is built around: too expensive to be an efficient mill engine, too large and evasive to be dead if the mill never matters. Ten cards is a meaningful chunk against a deck already low on library, and against anyone with graveyard payoffs it can hand the opponent exactly what they wanted, which is the sharp edge on any mill card that also functions as a beater. The honest read is that the body carries the card and the mill is upside, a reversal of most mill designs, where the effect is the point and the body is an afterthought.