Capell resembles a large spherical mutant, with five eyes and mouths, the eye/mouth will change each time Capell blinks/closes it's mouth, Capell's smaller forms will have two less mouths/eyes, with the smallest having only one.
When in battle, Capell will constantly bounce on the ground from a large height, attempting to crush Eve with its body.
Since Eve has no way to defeat Capell bare-handed, she has to reach and push the boxes that appear on top of the arena to defeat it. Despite having to reach the very top of a two-screen-high arena and deal with ledges disappearing during her ascent, Eve is in no danger of dying from fall damage thanks to a one-block-deep pool of water comprising the arena's floor. Touching the water resets the ledge and block distribution into one of three patterns, and also spawns/despawns Capsules placed midway up most routes to the blocks. As Capell is crushed by blocks, it splits into smaller sections with faster and more erratic bouncing trajectories, making Unchained DDF increasingly necessary to make a safe ascent.
Capell's second fight is considerably easier thanks to Andreia. Water Trap can easily leave Capell and its smaller forms vulnerable, while the water pool allows for easy SP restoration.