Accelgor (5e Creature)
From D&D Wiki
Small monstrosity, any alignment
Shed Skin. The accelgor has advantage on saving throws to end effects currently active on itself.
Unburden. While the accelgor is below half its hit point maximum, its speed is doubled, it gains a +2 bonus to AC, it has advantage on Dexterity saving throws, and it gains an additional action on each of its turns. That action can be used only to take the Attack (one weapon attack only), Dash, Disengage, Hide, or Use an Object action.
Multiattack. The accelgor makes three water shuriken attacks.
Water Shuriken. Ranged Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) slashing damage.
An accelgor will evolve from a shelmet when its protective shell is stolen by a rival karrablast. Upon this evolution, the accelgor's speed becomes its greatest advantage, allowing to fire off a great number of attacks om quick succession, dodge enemy attacks, move around with incredible speed.