Wall of Lost Thoughts

Mill decks live and die by how much they can advance their clock without dying to the aggression they've done nothing to slow, and a 0/4 that mills four while it lands answers both problems in the same slot. The design logic is tidy: Defender means the card is never a threat, so all of its investment routes into stalling and self-mill, and the enters trigger front-loads the value on arrival rather than asking you to keep the body around. That decoupling is what makes it a mill workhorse; the four cards are banked before combat ever happens, so trading the wall away in a block costs you nothing you hadn't already collected. It also targets any player, which quietly makes it a self-mill enabler for graveyard strategies as readily as a piece of the disruption engine. The four toughness matters more than the mill number for how long the card holds a ground stall together, outlasting most of the small creatures a mill deck actually fears. It sits in a lineage of blue defensive mill: the wall that buys time while chipping incremental progress off a library, built to do two cheap jobs rather than one job well.