Drakea's marginal note on an indestructible NPC — tied to a shield, dragged out a door, exploded five times — becomes Carl's precedent.
Drakea's twenty-second-edition annotation to the NPC chapter of The Dungeon Anarchist's Cookbook is the practical half of the lesson Azin began. Their crew found an indestructible NPC and tied him to the front of their shield; the Nagas patched it overnight with no announcement and the man simply disappeared. Going back to the church to grab him again, they found the building would not release him — dragged out the door, he exploded and was reborn, five times over, before they gave up. It turned out he knew the password to the safe holding the key to the stairwell chamber.
The note reaches Carl at exactly the right moment. It explains why Growler Gary cannot cross his own threshold, warns that the value locked in such an NPC is worth systematic effort, and — read alongside Drakea's characteristic contempt for the snakes who patched their exploit — tells Carl that this kind of puzzle is deliberately placed and deliberately cruel. Drakea's own solution was cheerful about the abuse involved; Carl's is not, but it is the same solution.
Never seen; a voice in the Cookbook's margins, emotional and verbose and fond of the word 'Ha.'
The past crawler whose exploitation of an indestructible NPC is the precedent for what happens to Growler Gary.