Swampfire is a Methanosian from Methanos (referring to methane). Methanos is described as a swamp planet that has an atmosphere thatis toxic to most life forms. Methanos also has large underground deposits of methane gas that sometimes escape and create geysers of flame that shoot up to twenty feet into the air.
Swampfire is a plant-like alien with a flame-patterned head. He is described as a living swamp. Swampfire is shown to be taller than most humans. When a limb is removed, it can reattach it. When lasers are fired, it can regenerate. Its alien speices in a Methanosiom.
He possesses the power to shoot fire from his palms, has superhuman strength, controls plant life through a type of gas, and vast regenerative powers to the point of intangibility. His fire is created by igniting methane naturally produced withing his body, which makes him stink. His regenerative ability also allows him to tunnel underground in vine form, grow his feet to root into the ground, heal his limbs, and passing through prison bars. These fire blasts and semi-intangibility have replaced Heatblast and Wildvine, making Swampfire Ben's new main alien for his flexibility.
Heat would only make him very hot it burns other allies.
Ben first transforms into Swampfire in Ben 10 Returns (Part 1) when the omnitrix is recalibrated.