Axel, the Flurry of Dancing Flames

Nobody. Axel is a Nobody, and hence feels no emotion. Charisma throws against Axel have a disadvantage, and Axel has a disadvantage on Charisma saving throws.

Burn, Baby! If Axel is hit by any fire damage, he gains a +1 to hit next skill check.

Multi-attack. Axel makes 3 attacks. Two Chakram Throws and one Fire Flash.

Chakram Throw. 5-15 ft. range, one target, + 3 to hit. Deals 9 (3d4) slashing damage.

Fire Flash. Axel lights his Chakrams on fire and locks onto a target within his movement range. Axel proceeds to then dash behind the target, and throw Eternal Flames at them. + 4 to hit, deals 10 (2d6 + 3) fire AND slicing damage to the target on hit. If Axel uses this attack on a target who hasn't seen it for the first time, he has an advantage to hit. This attack can be used as a counter.

Overtaker. Axel covers the floor of his ring of fire in fire. Axel isn't affected by this, but anyone else who isn't immune to/resist Fire damage will take 7 (4d4) Fire damage at the end of their turn while they stand on the floor, but this damage cannot cause anyone to be knocked unconscious/die. Details on removing the fiery floor are under the Dash to Ash attack.

Overcooked Slam. Axel slams the ground with Eternal Flame, causing a large pillar of fire to erupt from the ground. Axel's slam has a range of 5 ft., while the pillar hits 5 ft. around Axel. The slam has a +3 to hit, while the pillar requires a DC 14 Athletics check. The slam deals 7 (2d6) bludgeoning damage, and the pillar deals 13 (2d8) fire damage.

Heated Ambush. Axel jumps into the walls of his fiery ring, and waits up to 2 turns waiting behind the walls. Afterwards, Axel jumps out at any angle he wants, and uses one of three actions. Whichever action Axel decides to use has an advantage to hit. Can be used as a counter.
1: Fire Flash
2: Overcooked Slam
3: Dash to Ash

Dash to Ash. Only usable during Heated Ambush. Axel jumps out from the fire and dashes right at a target, leaving a trail of fire behind himself. Anything in his path must either dodge out of the way (DC 13 Acrobatics) or stop him in his track (DC 17 Constitution). If you fail either of these, you take 16 (3d8) fire damage. If you manage to stop Axel, you can follow it up by challenging him to a roll of either Acrobatics, Strength, Athletics, or Dexterity. If Axel wins the roll, he follows this up with one of his counter attacks. If the target wins the roll, they land 2 hits with their equipped weapon (or fists, or prepared spell), and as extra if Overtaker is active, the fiery floor disappears until Axel uses Overtaker again.

Final Flame. Axel's desperation attack, can only be used while under half health. Axel singles out a target inside his fiery arena, and waits a full turn before doing anything else. During this time, Axel's AC is raised to 24 and he cannot be staggered. Once it cycles back to his turn, Axel launches a flurry of 13 flaming chakram attacks at his target, each Chakram having a + 3 to hit and dealing 11 (3d4 + 2) fire and slashing damage. To finish it off, Axel slams the ground, causing a shockwave across the arena that requires a DC 16 Athletics check to dodge, and deals 17 (3d8) fire damage on fail, dealing none at all on success. On top of all that, the shockwave activates the effect of Overtaker. After this attack, Axel will have his next turn skipped, will stagger to any attack you hit him with, and his AC is permanently cut in half for the rest of the fight.

Stagger. If you roll at least 7 over your chance to hit Axel, he will stagger, being briefly stunned and allowing the attacker to attack again. If Axel is staggered twice, he's launched briefly into the air, making him harder to hit again. If Axel is staggered a whopping 4 times, he will break out of the Stagger and unleash one of 3 counter attacks chosen at random, and the attacker's turn instantly ends, no matter how many actions they have remaining. (Look for what attacks can be used as a counter under the attack section.) 

I'm so FLATTERED! If Axel enters combat, he'll surround everyone in the fight, himself included, in a giant ring of fire. If anything other than Axel touches the ring, they take 21 (4d6 + 5) fire damage.