First and foremost, Lavos is in a REALLY good spot power and survivability wise. Some minor usability tweaks would make him the most perfect he could probably be, however.
First and foremost, having to re-fill Lavos' vials after every cast really ends up only being detrimental. Either you 1: Stop and refill the vials, interrupting normal movement, offense, and defense in the process, or 2: Use an ability without refilling your vials (Either accidentally by forgetting, or having to use an ability in an emergency situation) and lose out on a portion of the damage and status that ability could