Heal Extenders help with healing Dead Land, and are in some cases the only way to heal Super Dead Land. They must be healed before they can be activated; either healed directly by healing power, or by healing one of its adjacent tiles (vertically or horizontally only).
Once healed, tapping them will cause them to immediately heal all four surrounding (vertical and horizontal) land, as indicated by the arrows on the Heal Extender. If left untapped, the Heal Extender will automatically activate after approximately 5 seconds.
Note that any quest which involves activating Heal Extenders will only register a manual activation. Therefore, letting a Heal Extender activate on its own may make it impossible to complete that particular quest.
Heal Extenders can only be found in levels.