From Guild Wars 2 Wiki
Heat Stone is one of many items needed to craft a Pet Plantling. It's also used in Chuka and Champawat IV: Baby Book to help keep the tiger cubs warm.“
A simple heat stone isn't quite enough to channel the sweltering temperatures of the deep Maguuma Jungle.
— In-game description
The recipe can only be crafted once per day per account, on the standard daily reset.
|Destroyer Heated Stone||Ascended||Mystic Forge||0|