. Even the basic common Mephit in the Monster Manual has Fast Healing, a spell-like ability or two, and the power to summon help when needed.. This isn't even to mention their fly speed, or their breath weapon. Actually, with the way their breath weapon works, they work better played as individual than as swarmers; tracking a swarm of creatures is hard enough, give each one an ability on a cooldown and it becomes harder, make the cooldowns random and it becomes nearly impossible.