Spellcasting. Akron's spell casting ability is intelligence. the dc is 20 for any spell he casts unless noted in these margins otherwise. 

Once/day-Elemental Bane(4th),Wall of fire(4th),Heat Metal(2nd)

At will: Investiture of lava(does not require concentration checks)

Tempered Will-Concentration checks are not required while Akron is using Investiture of Lava. He can cast another spell that requires concentration while using Investiture of Lava.

Magma Boy- Akron can turn his fists into magma. 

Stoic Training- Akron has 5 levels in monk. He gets 5 ki points to use, they become available after a rest. 

Legendary Resistance- (3 per day)if Akron fails a saving throw, he can choose to succeed in that saving throw instead. 

 Magma Unarmed strike: +15 to hit, reach 10 ft., 1 target. Hit: # (13d4 + 30) bludgeoning damage. Con save 15, 10d6 fire on fail save, half if success or target makes dex save dc 14, if failed knocked back 10 ft. 

Flurry Of Blows-(1 ki point) After attacking, Akron can spend one ki point to make two Magma Unarmed Strikes as a bonus action.

Extra attack- When Akron uses the attack action, he can make two attacks. 

Heat up- Akron's next Magma Unarmed Strike has double the range, up to 20 ft. 

Flurry Of Blows-(1 ki point) After attacking, Akron can spend one ki point to make two Magma Unarmed Strikes as a bonus action.

Burn off- If attacked, Akron can choose to take no damage from that Melee or ranged attack. In addition, any poison in his system is removed. Once per round, resets at start of Akron's turn

Deflect Missiles- can use reaction to deflect or catch a missile when hit with a ranged weapon attack. Once per round. resets at start of turn. 

Admiral Akron can take up to two legendary actions per round

Legendary Action

Re-ignition- Akron casts Investiture of lava

Overburn- Akron turns his fist into lava and makes an Unarmed Strike at a creature within 10 ft of him.+8 to hit. If the attack hits, target takes 10d4 + 8 bludgeoning damage plus makes a constitution saving throw dc 16. target takes 14d6 fire damage on a failed save, half on success. If Investiture of Flames is not active, this costs two actions. 

Blowing Smoke(2 actions, loses legendary actions for the next round)- Akron casts Incendiary Cloud, then loses the ability to use legendary actions for the following round.