core infused berserker

Shielding core. At the start of its turn, the berserker gains 5 temporary hit points unless it has used its core adaption feature since its last turn.

Labyrinthine Recall. The berserker can perfectly recall any path it has traveled.

Reckless.  At the start of its turn, the berserker can gain advantage on all melee weapon attack rolls it makes during that turn, but attack rolls against it have advantage until the start of its next turn.

Multi-attack. The berserker makes two Gauntlet strikes

Gauntlet strike. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 10 (1d8 + 6) bludgeoning damage. 

Core adaption. When the berserker takes Fire, cold, acid, lightning, or thunder damage it can grant itself resistance to that damage type till the start of its next turn. 

The berserker can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The berserker regains spent legendary actions at the start of its turn.

Leap (Costs 1 Action). The berserker jumps at half its speed to an unoccupied space, this movement does not provoke opportunity attacks. 

Vent core (Costs 1 Action). If the berserker has used its core adaption ability it can vent the cores built into its body. When it does so it loses the resistance it gained from core adaption. Each creature within 10ft of the berserker must make a, DC 15 Dexterity saving throw, taking 9 (2d8) element damage on a field save and half as much on a success. 

Ground slam (Costs 2 Action). The berserker slams its gauntlets into the ground creating a shock wave. Each creature that is standing on the ground within 30ft of the berserker must make a, DC 15 Strength saving throw or take 9 (2d8) thunder damage and be knocked prone.