This is not available in 2024.
Transmutation
If put inside a Gelatinous Cube, if Enlarges the creature to tripple size (goes from 10×10 to 30×30 feet).
Unknown if it will work on other oozes.
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Created from the skull of a Duergar Dwarf, preserving their ability to Enlarge themselves.
Encased in a glass ball, to protect it from the acid of the Gelatinous Cube.