Mystic Frog

The Mystic Frog is a Critter that spawns in the Jungle surface (does not spawn in cavern layer). It is one of the few creatures detected by the Lifeform Analyzer. When Purification Powder is applied, it turns into the The Mystic Slime.The Mystic Frog glows a faint light when in the dark. If attempted to catch with a net, it disappears into a puff of smoke, similar to the behavior of a critter spawned from a statue.

Spawning

 * Gnomes and Water Candles and/or Battle Potions can be used to increase its spawn rate, note that this also will increase the spawns of enemies which can kill it.
 * Having a town of 3 or more NPCs nearby will greatly reduce enemy spawns while also increasing critter spawns.