Astral Font Water

Starlight Spellcasting -
Water removed from the Astral Font glows faintly for 24 hours, shedding dim light in a 5-foot radius. A spellcaster who quaffs an ounce or more of the glowing water must make a DC 16 Wisdom saving throw. On a failed save, the creature takes 24 (7d6) psychic damage. On a successful save, the creature gains the ability to cast one spell of their choice from the cleric spell list or the wizard spell list. The chosen spell, which must be of 7th level or lower, uses the caster's spellcasting ability and requires no material components. Once the spell is cast, it fades from memory. A creature can gain only one such spell at a time and can't benefit from drinking the pool's water more than once every 24 hours.