Underworld Gatekeeper

The Underworld Gatekeeper (冥界ガーディアン Meikai Gādian, "Netherworld Guardian") is an Underworld mini-boss in Kid Icarus: Uprising.

Physical Appearance
When inactive, the Underworld Gatekeeper's mechanical parts are folded into itself, giving it a compact, round appearance with sharp edges at the bottom.

When active, the Underworld Gatekeeper's three segments rotate outward, revealing its inner guns and mechanical wings. During battle, it may also fold its upper segments backward and lower segment forward to propel itself like a jet.

Chapter 9: Medusa's Final Battle
The Underworld Gatekeeper appears as a last line of defense to prevent Pit from accessing Medusa's castle in the Underworld. After a long fight, Dark Pit delivers a swift kick to its side, finishing it off and causing it to explode.

During the battle, the Underworld Gatekeeper's primary strategy is firing a plethora of projectiles at its foe. It will do so by firing a barrage of orange orbs, blue beams, and slow-moving, red projectiles that home in on its target. It will also fold itself into a jet shape and zip across the screen to harm its opponent, though this attack is always preceded by a pink streak that reflects its flight path.

In addition, it can fire massive laser beams from between its upper segments, summon circular, green barriers that harm opponents should they make contact, and cast out large, electrical rings of energy. The battle will end after a short period of time has passed, regardless of whether or not it has received any damage.

Underworld Gatekeeper
''A magical construct designed to defend the Underworld Castle. While the guardian has powerful defenses, Dark Pit easily brings the colossus down by delivering a kick to the concentration of artificial nerve endings on its side.''

Trivia

 * Upon unfolding itself, the Underworld Gatekeeper vaguely resembles the Gorgon in its opened-up form from Star Fox 64.
 * The Gatekeeper possesses guns that appear similar to the Triforce, a possible reference to the Legend of Zelda franchise.