Geist of the Lonely Vigil

Defender is usually a permanent tax, a promise that the creature will never attack. Delirium turns that promise conditional: once four card types accumulate in your graveyard, the wall drops its defender clause and the 2/3 flying body starts swinging in the air every turn. The structure rewards a deck that was already filling its yard for other reasons, so the attack mode arrives as a payoff rather than a build-around; early in the game the flyer blocks, holds the air, and buys the time the delirium count needs to come together. What keeps the design honest is that the toggle is not permanent the way a counter would be: lose card types from your graveyard and the wall reverts, so the threat is only live while you keep the condition met. That tension (a blocker that becomes a clock, but only as long as you keep feeding the yard) is why it plays as a self-tending creature rather than a vanilla flyer. It belongs to the family of delirium cards that fold the graveyard-tracking requirement into a static unlock rather than a one-shot trigger, converting a bookkeeping threshold into a lasting shift in how the permanent behaves once the condition is on.