1 Eleven: Wow! A treasure room! Everything in here must be incredibly valuabe.
2 Dustin: The False Treasure Room. Every treasure in here is fake.
3 Eleven: So it’s all illusory?
4 Dustin: Yep. Just like my hopes and dreams.

Much of it looks and feels real. It's just that when it's removed from the Tomb, the incredibly valuable looking gems in the chests are revealed to be worthless. The thousands of platinum coins are even more devious - they are only revealed to be (relatively worthless) copper coins when transported more than 13 miles from the Tomb!

The idea here is that the players might conclude they've made their way far enough into the Tomb and this is the final treasure. They load up the gems and platinum and vamoose...

Only to be laughed at by the GM when they reveal that they fled with worthless junk before even reaching the true climax of the adventure!