The saferoom delivery point where floor prizes arrive, holding the Gate of the Feral Gods and Donut's spellbook.
The dungeon mailbox is the fixture in each saferoom through which the dungeon delivers prizes, purchases, and correspondence. At the start of The Ceasefire on the Faction Wars floor, Carl retrieves the Gate of the Feral Gods from it before the chapter's conversation begins.
Princess Donut's haul comes through it as well. After tossing the Boonie Hat and Ghillie Suit into her inventory, she reaches into the back of the mailbox and pulls out her Spellbook of the Floor prize, which turns out to contain the anti-air spell Flak — a prize Mordecai praises but forbids her from reading until the team has planned.
A dungeon-issued mailbox in the saferoom, deep enough that prizes sit at the back of it.
Delivery point for the team's floor prizes and rewards.