Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny fire gecko. The swarm can't regain hit points or gain temporary hit points.   Trail of Flame. Whenever the swarm moves more than 10 feet on its turn, it leaves behind a trail of fire in the spaces it moved through. The fire burns for 1 minute and deals 1d4 fire damage per round to any creature that enters or ends its turn in the fire.   Fiery Demise. When the swarm is reduced to 0 hit points, it explodes in a burst of fire. Each creature within 5 feet of the swarm must make a DC 13 Dexterity saving throw, taking 2d6 fire damage on a failed save, or half as much damage on a successful one. The explosion ignites flammable objects in the area that aren't being worn or carried.