Fireplace was added in Beta 50.1. Previous Versions can be found here.
Fireplace has a combination of Transparency and Shock, an effect that triggers every time you cast a spell with a base cost of at least 2G. When doing so, Fireplace will restore 3 HP to itself.
This makes it a rather strong card. It's likely to survive on its first turn due to Transparency, and after attacking a monster with it on your next, you can use spells to heal it up. While you need to provide the healing yourself unlike Candy (which heals as much, but only at the end of your turn), you can heal it as many times as you want and whenever you want in the same turn.