Sage of Mysteries

Constellation was the mechanic that turned "an enchantment entered" into a repeatable trigger rather than a one-shot, and this is the card that welds that structure to a mill engine. The 0/2 body is the tell: it exists to block and hold the ground while the ability does the work, so every aura, God, and enchantment creature that lands sends two more cards to a graveyard. The only decision the trigger offers is whose library it points at, and both readings have a home: aim it at yourself to feed escape, delve, or other graveyard payoffs, or aim it at an opponent when the plan is a slow deck-out. Getting it down early matters more than anything else it does, because it wants to be on the board first, catching every enchantment trigger that follows before the count starts climbing. What it never does is end a game on its own; it is an accelerant, and its output is capped entirely by how many enchantments a deck can chain. That dependency is the design's honest limit. In a shell flooding the board with cheap enchantments it grinds two cards at a time, relentlessly; in a deck with three enchantments total it is a wall that does nothing else. The mill is only as deep as the enchantment count is wide.