Andrius Sinn

Epic Boss Hit Points. Increase Andrius Sinn's starting hit points by 175 for each player character above four, or reduce its starting hit points by that same amount for each player character below four.

Evasion. When Andrius Sinn is subjected to any effect that allows it to make a Dexterity saving throw to take only half damage, it takes no damage when it succeeds on the saving throw, and only half if it fails.

Inperceivable Speed (Optional). All creatures in a combat encounter with Andrius Sinn only have one minute to declare their action on their turn and roll Initiative at disadvantage if they have less than 20 Dexterity. If they fail to declare their action in time, their action is skipped, and attacks against them have Advantage until the start of their next turn. As a free action, upon being reduced below half of his maximum hit points, Andrius may reduce the time limit to 40 seconds. 

Ki-Empowered. Andrius' attacks are considered magical to overcome resistances and immunities.

Raijin Style 1st Technique: Thunderous Momentum. After Andrius takes the dash action, his first attack has advantage and deals a bonus 5d8 thunder damage, and he may knock the target 5 ft. away from him. If the target is knocked into another creature, they take half the Lightning and Thunder damage dealt to the original target.

Raijin Style 2nd Technique: Speed of Lightning. At the start of a new round, as a free action, Andrius may use the dash action. He may also move up to his movement speed and make an unarmed strike. Whenever Andrius makes an Epic Action, he may move up to half of his current movement speed. 

Raijin Style 7th Technique: Lightning God Armament (Twice per long rest). Gauntlets made from raw electricity form around Andrius' hands and, for 1 minute, any instance of lightning or thunder damage output by Andrius deals a minimum of half the maximum damage. 

Raijin Style Ultimate Technique: Avatar of the Storm (Recharges after a Short or Long Rest). If Andrius is reduced to 0 hit points, his current hit point total instead resets to 500 hit points, he recharges his ki, and he regains any expended uses of Legendary Resistance. Additionally, Andrius can now use the options in the "Mythic Actions" section for 1 hour. 

Reactive Perception. Andrius has 2 reactions rather than 1. If he has expended them both, as a free action, he can make a DC 15 Wisdom saving throw, which, upon success, refreshes one of his expended reactions. On a failure, he does not regain his reactions at the start of his next turn. Each time this is used, the DC increases by 5 and resets to 15 at the end of his turns.

Sacred Monk Art: Battle Spirit Revival. If Andrius lands a critical hit against a creature, he regains Hit Points equal to the damage, clears one condition or effect of his choice, and has his Critical Hit threshold decreased by 1 until the end of his next turn. If the attack hits multiple creatures, he only regains Hit Points equal to the damage dealt to the primary target of the attack.

Andrius Sinn always takes his turn on Initiative count 20, unless he is in his demi-plane, in which case he takes his turn on Initiative count 25. On his turn, Andrius Sinn can use his movement and interaction as normal. However, he does not take an action or Bonus Action on his turn unless forced to do so by a spell or other effect. Instead, the Algorithm takes one of the following Epic Actions at the end of each player character's turn:

Raijin Style 4th Technique: Storm Flurry. Melee Weapon Attack: +16 to hit, reach 5 ft., one target. Hit: 16 (2d8 + 8) bludgeoning damage plus 16 (4d8) lightning damage. He may make two attacks whenever he takes this Epic Action. The lightning damage is also dealt to another creature within 5 ft. of the original target. It may then jump to another target within 5 ft. of the second, though it cannot jump back to the original target. 

Raijin Style 5th Technique: Coiling Eel Bindings. Melee Weapon Attack: +16 to hit, reach 5 ft., one target. Hit: 16 (2d8 + 8) bludgeoning damage plus 16 (4d8) lightning damage. If this attack connects, he grapples the target. While the target is grappled in this way, it has the Prone, the creature will take 12 (4d6) lightning damage whenever Andrius makes an Epic action, increased to 33 (6d10) lightning damage if he chooses to use his epic action to amplify the charge, and attacks against Andrius that miss will instead hit the Grappled creature. He cannot take any action that would grant him the Dodge effect while grappling with a creature.

Raijin Style 6th Technique: Split Second Detection. Andrius takes the Dodge action, benefiting from it until he next takes damage or until the start of his next turn. While in this stance, he may use an unarmed strike as a counterattack against anyone who makes a melee attack against him while dodging. He has an advantage when countering a target that misses their attack against him. If his counterattack hits, it refunds the reaction used to make it.

Raijin Style 8th Technique: Thunder Cloud Burst (1 /Round). Melee Weapon Attack: +16 to hit, reach 5 ft., one target. Hit: 20 (3d8 + 8) bludgeoning damage plus 33 (6d10) lightning damage. The creature is knocked back 30 ft. in a straight line from Andrius. Any creature the target hits as it is launched takes damage equal to the lightning and thunder damage dealt by this attack and is knocked Prone.

Epic Resistance. Andrius chooses one condition, spell, or other effect currently affecting him and rolls 1d20. On an 11+, the effect ends on it. Andrius can use this action even if it would otherwise be unable to take actions, its actions are being controlled by another creature, or if a spell or effect alters its game statistics.

Raijin Style 3rd Technique: Wind Reversal. Andrius deflects any ranged weapon attack or spell attack, reducing the damage by 3d10 + 15. If the deflected attack was a single-target ranged attack and its damage is reduced to 0, Andrius sends the projectile back, targeting a creature within 80 ft. that he can sense. It deals damage equal to the original damage roll of the projectile, plus Lightning damage equal to the excess amount by which the damage was reduced beyond 0. 

Raijin Style 6th Technique: Counterattack.  Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 12 (1d8 + 8) bludgeoning damage plus 8 (2d8) lightning damage.

If Andrius' Avatar of the Storm trait has activated in the last hour, he can use the options below as Epic actions. He also gains an additional use of his Raijin Style: Lightning God Armament. 

Raijin Style 4th Technique Evolved: Godspeed Flash. Andrius uses Strom Flurry, making three attacks instead of two, and it can arc to an additional creature so long as that creature is neither the original, second, or third target. 

Demi-Plane Manifestation: Transcendent Current. Once Andrius uses Raijin Style Ultimate Technique: Avatar of the Storm, he may manifest his demi-plane, known as Transcendent Current. This is a 60 ft. diameter spherical plane that acts as a lair for 1d4 rounds.