Arthel Sharpe

 Indomitable (2/day). A beam of pure light from on high envelops Arthel as he instead succeeds a failed saving throw. 

Judged Worthy (Recharge: 5-6 on a d6). Arthel's sword glows with heavenly confirmation and explodes into light on first impact, dealing 4d6 +6 radiant damage. The creature must make a strength saving throw or be pushed back 10 feet and knocked prone. 

shield of faith (1/day) (Concentration) - An orb of pure light emanates from Arthel's armor, giving him an AC of 23. [Constitution saving throw]

Multiattack. Arthel makes two melee attacks and one ranged attack.

Greatsword. Melee Weapon Attack: +10 to hit, 2d10+6, reach 5 ft., one target. radiant damage. 

Radiant Hammer. Ranged melee attack. +8 (1d8 + 3)

Purge: if someone is marked, he can absorb the mark for 10HP (has to be a light while he's >50HP and dark while he's <50HP). 

Repulse - if two or more characters are around Arthel at the end of a player's turn, he can push them all back 30 feet. 

Retribution (2/day) - when hit by a ranged attack, half of the damage is reflected at the user. 

Riven Soul - when damaged by radiant damage, Arthel can respond by emitting an orb of pure darkness in a 15 foot radius dealing 2d6 + 2 damage to all in the sphere (dex save 13). 

 LEGENDARY ACTION (2/round): 

Radiant Arrow - from the sky rains down a heavenly arrow,  - 8 dmg if hits

VILLAIN ACTIONS

(Round 1) Light and Dark - each character rolls a D4; 1 or 2 mark them light, 3 or 4 mark them dark [beginning]

(Round 2) Bow down -- every character rolls another D4 -- 1 or 2 marks them light, 3 or 4 marks them dark (they will offset if one dark, one light); they must succeed on a wisdom saving throw (13) or be knocked prone 

(Round 3) Consider Yourselves Judged! -- Radiant light from Erathis herself radiates around each player, dealing 4d8 radiant damage (+ 4 for each mark) on a 13 dex save

(Half health) Cracks in Arthel's armor and cuts on his body reveal how even his body has been corrupted. He now begins to dim and darken with ink-like blood oozing out of his wounds. His sword will turn dark and he will be able to absorb - as a bonus action - the dark shrouds.