Gladiator

Killers, entertainers, a gladiator.  Gladiators are powerful fighters born from the coliseum, a person trained not only kill, but to do so in an entertaining way.  Those who fight in this way often do it not only to sway a crowd, but to prove to themselves and others that they are the most capable warriors in the ring.  To survive in the ring, you have to be as strong as an elephant, more cunning than an eagle, and have the speed of a lion.  Without the power to overcome, the gladiator would fall and their name would be lost to the dust.  

Unleash Hell

When you take this subclass your gladiator powers begin to show in gruesome and powerful ways.

Beginning at 3rd level, you gain a d4 as a Gladiator Die for your abilities. You also gain proficiency in the Performance skill.

When rolling damage on a melee attack, you can add extra Thunder damage equal to a roll of your Gladiator Die.  You can use this a number of times equal to your Strength modifier (minimum 1).  The number of uses resets on a short or long rest.

Two Men Enter. One Man Leaves.

Trap your enemies in the arena where you are at your strongest.

Beginning at 7th level, Your Gladiator Die increases to a d6, and you gain the ability to use Thunderdome.  

Thunderdome. As an action, erect a visible dome of thunder in a 15ft circle centered 10ft in any direction from you with walls that are 1ft thick.  Ranged attacks that pass through either side of the dome are at disadvantage.  If a creature (including yourself and allies) wants to leave the dome before the effect ends, they must make a Constitution saving throw with a DC equal to 8 + your proficiency + your Constitution modifier while moving into a wall.  On a failure, the creature is pushed 5ft towards the center of the circle and takes thunder damage equal to an amount of Gladiator Die equal to half your level (rounded up).  On a success, the creature takes half damage and is able to exit.  If a creature uses magic to displace themself outside the dome, they can automatically pass, but still take half damage.  The dome releases after no creatures in the dome make attacks against another creature beginning at the start of your turn and ending at the start of your next turn, if you leave the dome, or if you go unconscious.  You are unable to erect another dome until the first one ends.

You can use Thunderdome a number of times equal to your Proficiency bonus per long rest.

While under the effects of Thunderdome, you can use your Unleash Hell without it counting against the number of uses you have per long rest.

Lord of the Arena

You're mastery of the arena allows you to grant power to your allies within your arena.

at 10th level, your Gladiator Die increases to a d8.  Also, you gain the ability to use Gladiator's Roar in place of one of your attacks.  You can use Gladiator's Roar a number of times equal to your Constitution modifier (minimum 1).

Gladiator's Roar. Special Action.  You let out a battlecry to rally your allies.  Any ally that hears this is rallied.  They gain temporary hit points equal to two rolls of your Gladiator Die and walking speed of each ally is increased by 10ft.  If your allies are under the effects of Thunderdome, your allies gain the ability to add your Gladiator Die in Thunder damage to their melee attack damage. This effect lasts for 1 minute and cannot be used if you are silenced.  This also does not affect allies who cannot hear you.

The number of uses resets on a long rest.

The Blood Of My Enemies

Bathe in the blood of your enemies as they fall before you.

At 15th level, your Gladiator Die increases to a d10.  Also, When you reduce a creature to 0 hit points, you now gain temporary hit points equal to (2 rolls of your Gladiator Die + your Constitution modifier) and regain 1 use of Unleash Hell.

Am I Not Merciful?

Those who defy you must be prepared for their end as you are the judge, jury, and (most importantly) the executioner.

When you reach 18th level, your Gladiator Die becomes a d12. You can also use the Executioner's Chain feature as an action. 

Executioner's Chains. Action.  Choose a creature under the effects of Thunderdome.  This creature must make 3 saves using their lowest physical stat (Strength, Dexterity, Constitution) with a DC of 8 + your proficiency + your Strength and increasing by 5 for each roll.  On a success, nothing happens.  On a failure, an ethereal chain emerges from the ground and grabs the target.  If one chain hits, the target's speed is reduced by half and attacks against the target have advantage.  If two chains hit, the target's speed is reduced to zero and the next attack is a guaranteed critical hit.  If all three chains hit, the target is incapacitated and the next 3 hits are guaranteed critical hits.  This effect lasts until either the effects of Thunderdome end or if the creature is hit an equal time to the number of chains connected to them.

You can use this feature any time you are under the effect Thunderdome, but only once per use of Thunderdome.