Altar of the Brood

The mill here is not a clock; it is a tripwire. One card per permanent enters slow, and any deck trying to grind an opponent's library down a card at a time will lose to itself first. What makes the trigger dangerous is that it counts every permanent you control, not just creatures, not just spells, regardless of whether it was cast, copied, or conjured. Pair it with anything that floods tokens or copies onto the battlefield in a single turn and the count stops being incremental: a board of dozens of permanents, generated repeatedly, empties a library before the engine can be answered. This is why the card lives almost exclusively in combo shells rather than control ones. The body is irrelevant (it has none) and the cost is trivial, so the entire design rides on the multiplier you attach to it. It is also the rare mill payoff that wins through synergy with token creation rather than through dedicated mill engines: there is no Glimpse the Unthinkable damage to scale, just a count that explodes when permanents arrive en masse, which makes it a reliable alternate kill in decks already churning out wide boards for other reasons. Outside that context it does close to nothing, and the split between those two states defines it: a one-mana artifact harmless on its own and lethal the instant the right enabler shows up.