Coily Rattler is the boss of Wild World in Kirby: Triple Deluxe. He is a large serpent statue that was once revered as a god by the Floralians. However, Coily Rattler was corrupted by evil magic which made a twist in his mind, turning him into a scourge in Floralia.
Coily Rattler is a golden snake made up of 12 pieces: a head, a tail tip, four rounded connectors, and six hexagonal connectors. The round pieces are adorned with royal blue stripes. His orange head has half an aquamarine orb sticking out the top, with a red band wrapped around it. The snake's eyes (which are not reptilian) are yellow with black pupils. The serpent has a forked tongue and six teeth in his bottom jaw. The hexagonal pieces have golden marking on them, in either a scale-like pattern or a rectangular pattern.
In Dededetour, Coily Rattler's body takes on a pearl-platinum color palette, with golden stripes, and a dark blue half-orb protruding from his head. The red band surrounding the serpent's half-orb bends upward into horns. In this form, the markings on the hexagonal pieces change to either a diamond-like pattern or an arrow pattern.
Coily Rattler's hologram form in Kirby: Planet Robobot portrays him as green with a blue head.
Coily Rattler is fought after Kirby makes his way into the snake temple and approaches the temple's core. Coily Rattler is at first seen as a statue, but then he is reawakened by Taranza. Revitalized, Coily Rattler falls, reassembles his body, climbs up one of the pillars, and then jumps onto the platform.
Coily Rattler starts the battle by spitting three volcanic rocks at Kirby; these can be inhaled to acquire the Fire ability. After he hisses, the boss will slither across the platform and off the screen; due to his winding movement, the snake's body won't touch the wider areas on the platform, making these spots safe to stand on. Coily Rattler will then return to the stage, then quickly lead off-screen. He will attempt to fall from the sky and land on Kirby. After another hiss, the serpent approaches the hero and attempt to strike him with a flurry of blows from his tail. This attack causes heavy damage if not avoided or guarded. Coily Rattler will then spit more rocks and slither across the screen again—instead of returning to the platform, it will coil up a background pillar and spit rocks at the hero from a distance. After this, his attack pattern will loop.
When 50% of the serpent's vitality is depleted, Coily Rattler, enraged, changes his pattern completely. The boss will coil around the platform and travel off-screen. Like his slither attack, Kirby can avoid him by standing in certain spots. Upon Coily Rattler's return in the background, his body will separate into 12 individual pieces; each piece will drop from the air and hit the platform (Their assault will leave behind stars that can be used by Kirby to damage the boss.), with the boss's head pausing for a few seconds after landing. Once he has reassembled himself, it will form a flaming ring of parts, then cross the platform moving up and down. Coily Rattler's head will then emerge from the top of the screen. After a few moments the boss will rush at Kirby -- if it misses, it will try a second time. If the pink puff is caught by the move, the snake will drag him all over the background before spitting him onto the foreground; this is Coily Rattler's strongest attack by far. After this, the serpent will slither on the platform's underside and emerge in the background, spitting rocks at Kirby. This move will be immediately repeated. After coiling across the platform again, the boss will coil around a background pillar and spit a volley of rock across the stage. When this is done, it will roll up into a ring and race across the stage, roll across the platform's underside and the roll back on top before stopping. However, depending on Kirby's position, Coily Rattler may roll only partway across the platform's underside, turn around, and roll back in the direction it came.
By this point, Coily Rattler will use attacks from his first and second phase interchangeably. Upon defeat, the serpent will coil up a background pillar and turn back into a statue. Each piece will explode, and his head will leave behind a Grand Sun Stone. Kirby will later encounter him in the second stage of Royal Road.
In Dededetour, Coily Rattler is called Coily Rattler DX, and he is fought at the end of stage four. In his intro, the boss will be seen slithering up the pillar in the background already, before jumping on the platform as King Dedede makes his way into the temple, then wonders why nothing's there, before the serpent lands behind him.
Coily Rattler DX's attacks are similar to those of the original Coily Rattler. He spits five volcanic rocks rather rapidly instead of three. It can slither and coil across the stage much more quickly, and slams the ground four, sometimes even five times instead of just once. The boss will rush at King Dedede when using his tail whip move.
After losing 50% of his vitality, Coily Rattler DX becomes more aggressive. During his segment-splitting attack, the boss's segments will swoop down at a rapid speed so King Dedede will have less time to react to their assault. Coily Rattler DX's head will swoop down up from the pit below. As a ring of now periwinkle fire, Coily Rattler DX is capable of changing directions to catch the player off guard.
Before the boss lunges from the ceiling, it will attempt to psych the player out by jerking his head before quickly pulling himself off the screen. If the snake catches the player, it will spit King Dedede directly into the screen.
Also in addition to his normal wheel routine, Coily Rattler DX will leap into the air in this form to hit Dedede.
Upon defeat, Coily Rattler DX merely shatters.