WIP of an upcoming creation (Patreon)

Currently working on this dungeon. Lore is still up for grabs! But what we've got so far is that teleportation magic is needed to reach the magic circle near the center-left of the image. Operating a few machines is needed to reach the main chamber that has a large interconnected pool.

But what fills this pool? I feel like water, acid, and lava are kind of overused so I'd like to avoid that. I'm thinking blood (arguably lame too)?, perhaps a liquid metal (molten gold)?

Do you have any inspiring input about the contents of this pool and perhaps the overarching theme of this chamber or encounter?