1 Mike: Through the illusory black sphere!
2 Dustin: Another inky black portal, like the previous ones that unknowingly led to instant death.
3 Dustin: And it’s guarded by an image of Tiamat, the most powerful evil dragon in existence.
4 Dustin: Isn’t there supposed to be some logic to understanding how to navigate the Tomb safely?
4 Lucas: By Gary Gygax? Hahaha!!

Clues in early D&D adventures could be a bit haphazard. At best there'd be some indication like a weird inscription, or a strangely posed skeleton to indicate that there's something you're meant to discover here, but it'd often be a crapshoot as to whether it was a good thing or a bad thing. Not to mention all the treasure hoards with delicious looking magical potions that turn out to be poison, or the cursed magical items.

Tiamat is a dragon goddess in the default pantheon of D&D gods, queen of all evil dragons. She has five heads, corresponding to the five colours of evil dragons: white, black, blue, green, and red. The game Tiamat is based on the deity Tiamat from ancient Mesopotamian mythology. She is variously imagined as either a primordial deity of the sea, or as an embodiment of primordial chaos who sometimes takes the form of a dragon.