Frost Prince is a Legends of Idleon item: quest reward.

Frost Prince | Idleon Toolbox

Frost_Prince

Made up of all the tokens that you collected after completing an NPC's entire questline. DONT SELL THIS ITEM

Proof that you mastered the art of the Trapping, Construction, and Worship skills. DONT SELL THIS ITEM

Proof that you collected all the coolest and rarest items that Frostbite Tundra has to offer! DONT SELL THIS ITEM

Prove your worthiness as the Tundra's Frost Prince.