Healing Block
The green '+' block. Match it and you get HP back, and you never need three of them: any match you make touching one clears it as well.
In detail
Block 10, the green plus. Ordinary match detection skips it, and it clears either by being matched directly or by sitting next to a regular match. The heal is a fixed amount per block, raised by Hag's Heart. One healing block is guaranteed to spawn per kill.
More in glossary
From the current development build. Content and balance may change before release. This public reference includes discoveries and does not reflect your personal unlocks.