From Warhammer 40k - Lexicanum
Hearths are powerful pieces of Leagues of Votann technology.
A Hearth is a blazing reactor that powers a Hold's defenses and sustains its light and life. Its fires are said to burn within the breast of all of its Kin, only extinguished if every last member of a Kindred falls.
- 1: Codex: Leagues of Votann, pg. 10