Drakkina, the last dragon.
She holds the largest hoard in Wunderwurld and the shortest route between everywhere. Her greatest treasure is not gold. It is a single fossilised egg, and the reason she cries at night.
A grieving dragon with logistical importance.
Drakkina is the last dragon. Her hoard is enormous, but the treasure she truly guards is the egg of her unborn child, fossilised, and never going to hatch. She is not a gag. The comedy around her comes from everyone else trying to navigate a den ruled by a dragon in mourning.
Her den is central to the whole cavern structure. It connects more caves than anything else down here, which makes it, technically, the shortest route between most places. Technically.
The shortcut nobody takes twice
The central den
Her cave joins the mines to the lagoons to the mine-carts to everywhere. On a map it is the obvious way through.
Only the lost arrive
In practice, only goblins who told their wives they did not need a map end up in the den.
She eats them
This is absurd, dark and specific, which is exactly why it works. Bring a map. Bring two.