Excal-heim
Ring
Legendary Requires Attunement
At the end of a long rest, you can lose 5 hit dice to change one damage type caused by spells you cast to another damage type.
This change doesn't alter any damage type related abilities, and lasts until you take a long rest.
Example: Lightning to Psychic
Until you take a long rest, all spells that would usually deal lightning damage, now deal psychic damage.
However, class abilities, magic items, and feats still behave as though the spell dealt lightning damage.
A mage who deals double lightning damage, casting Lightning Spear (2nd Level) would deal 2d8*2 Psychic + 2d8 force damage.