Ako, Isibazi Ascendant

Action Surge (1/Short or Long Rest). Ako takes one additional action. 

Innate Spellcasting. Due to his Guardian past, Ako can cast several spells at will. Ako can innately cast the following spells, requiring no material, verbal or somatic components, and without requiring concentration:

At will: haste, jump, longstrider

Reckless. Ako has become an unstoppable killing machine, and has abandoned his training, attacking with reckless abandon. At the start of his turn, Ako can gain advantage on all melee weapon attack rolls he makes during that turn, but attack rolls against it have advantage until the start of his next turn.

Regeneration. Ako regains 10 hit points at the start of his turn. If Ako takes acid or fire damage, this trait doesn't function at the start of Ako's next turn. Ako dies only if he starts his turn with 0 hit points and doesn't regenerate.

Legendary Resistance (2/Day). If Ako fails a saving throw, it can choose to succeed instead.

Multiattack. Ako makes two fist attacks OR one slam attack.

Fist. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 12 (1d10 + 6) bludgeoning damage. 

Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 6) bludgeoning damage. If the target is a creature, the target must make a DC 15 Strength saving throw or be knocked prone.

Rage (4/Long Rest). Ako enters a rage that lasts for one minute, ending early if Ako is knocked unconscious, incapacitated, or fails to make an attack roll or take damage on its turn. While raging, Ako has advantage on Strength ability checks and saving throws; resistance to bludgeoning, piercing, and slashing damage; +2 to damage rolls of melee weapon attacks (already factored in above).

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

Slam Attack. Ako makes a slam attack.

Intimidating Presence (Costs 2 Actions). Ako chooses one creature within 30 feet. If the target can see or hear Ako, it must succeed on a DC 15 Wisdom saving throw or be frightened of Ako until the end of Ako's next turn. This save is made at disadvantage if the creature has taken damage from Ako on the same turn. On subsequent turns, Ako can replace one of its attacks and force an additional saving throw to prolong the effect until the end of Ako's next turn. This effect ends if the creature ends its turn out of line of sight or more than 60 feet away from Ako. If a creature succeeds on its saving throw or the effect ends for it, it is immune to Ako's intimidating presence for the next 24 hours.

Bane of Magic (Costs 3 Actions). Ako can siphon his life spark into a burst of anti-magic energy. He screams, red lines of power coursing along his veins, and he emits a pulse of power in a 60-foot-radius sphere centered on himself. All creatures subject to a magical effect must make a DC 15 wisdom saving throw or the effect ends. If Ako uses Bane of Magic, his regeneration trait doesn't function on his next turn.