Regrowth is a Sustain ability that Skye must equip before casting. Upon casting, she emits a healing aura that heals ally agents in range. The ally must be in Skye's line of sight to be healed and any terrain that gets between Skye and the ally will prevent them from receiving the heal. Skye will not be healed by Regrowth.
Regrowth has a healing pool that is drained whilst the ability is used. The pool will not drain if the ability is not currently healing any allies. Skye can unequip then reuse Regrowth later on if there is still health remaining in the pool.