Killer gilas are large quadrupedal amphibians with ochre-colored skin, a tall fin with a pink membrane on its back, four pairs of frills on its face, and long tongues. They possess features of many real-world animals such as the Japanese giant salamander, the axolotl due to the frills on its face, and both the gila monster and Mexican beaded lizard due to their poisonous abilities. Starting with the Monsters series of games, they have become members of the Dragon family. The gilas have made regular appearances in spinoff games in the series, but did not return to the main series until X, like many other monsters.
Killer gila appears as a B-rank monster introduced during the second part of the Dragon Fest limited event. It will join the player in Chapter 4, Episode 2 of the event quests and it can participate in Bobonga's Battle Road as a party member. The killer gila can be fully awakened by completing the Wrothwood stage of the Dragon Island: Forest at any difficulty.