Dwarven Traits. As a dwarf, Volgroum has all dwarven racial traits.

Secret Runes of the Tower. While inside his tower, Volgroum gains power from the various runes that are located in the boss room. He gains resistance to all damage types and 20 temporary hit points (regenerates at the start of his turn) while the corresponding rune(s) are active. Runes are visible within the boss room and can either be disabled by a player within 5ft. (arcana check, standard action, DC 10) or destroyed (hit point: 15). Volgroum can reactivate a rune (unless it is hijacked) within 5ft. as a free action (once per turn). A disabled resistance rune can be temporarily hijacked for 1d4 turns using an arcana check by a player within 5ft. (standard action, DC 15). While a rune is hijacked, it's corresponding resistance becomes a vulnerability. 

Evil Blood. After years of practicing the dark arts, Volgroum's body is no longer normal. At the start of Volgroum's turn (or when he would have a turn) each round, all negative conditions are automatically cancelled. On a turn when one or more negative conditions were cancelled, Volgroum cannot perform an attack.

Dark Aura. During battle, Volgroum emits a dark aura causing a minor effect on those that oppose him. Any opponent that enter within 10 feet of Volgroum must succeed at a Wisdom saving throw (DC 12) or incur disadvantage on all attack rolls while they remain within 10 ft.

*Unpredictable Magic. After experimenting for years on the arts of magic, Volgroum is able to vary the type of damage that he produces. Any time he uses a magic attack or attacks with a magic weapon, replace the damage type by rolling a d10 and matching the result to the following key (this only replaces the base damage type, it does not impact any special effects):

(1) Acid | (2) Cold | (3) Fire | (4) Force | (5) Lightning | (6) Necrotic | (7) Poison | (8) Psychic | (9) Radiant | (10) Thunder

Spellcasting. Volgroum is a dark magician that has deviated from the normal systems of magic. For referential purposes, Volgroum is considered a 5th-level spellcaster. "Cursed Summoning" is considered a 3rd level ritual spell and Volgroum's cantrips are considered 1st level spells. Volgroum is not bound by spell slots or armor class restrictions.

SPECIAL ABILITY (Multi-Action) - Volgroum can take one standard action per turn, one additional attack per turn, and one additional non-attack standard action per turn.

Cursed Sword Attack. Melee Magical Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (1d10 + 3) varying* damage type.

If you roll a 1 to hit with this weapon you may re-roll (once per turn).

If you roll a 5, 10, 15, or 20 to hit this counts as a critical hit (double dice damage) and you have a damage modifier of +6 (instead of +3)

If you sacrifice a creature you control using this weapon then it emits a vicious energy wave. All opponents within 100 feet must succeed at a Wisdom saving throw (DC 15, minus 1 to DC for every 20 feet away) or take (1d4 + 3) psychic damage.

Knockback effect - If you deal damage with this weapon then it emits a kinetic energy wave. All opponents within 10 feet must succeed at a Strength check (DC is your Strength ability score) or be knocked back 10 feet. If there is another player, creature, or other object in the way then the target is knocked back as far as possible and takes 1d4 bludgeoning damage.

Cursed Ray. Ranged Evocation Magic Attack: +6 to hit, reach 120 ft., one (or more) targets. Hit: 8 (1d8 + 3) varying* damage type.

If you roll a 1 to hit with this spell you may re-roll (once per turn).

If you roll a 10 or 20 to hit, fire a second beam (+3 to hit / same damage type) at a different opponent that is in range (if no other opponent is in range then this bonus does not activate). Both beams deal critical damage (double dice damage).

Cursed Summoning. Special Conjuration Spell: As a standard action, Volgroum can gather his dark energy and make a quick summons ritual (see below for details). Cursed summoning can only be used up to once per turn.

Summoner's Connection. Conjuration Magic: Instantaneously switch locations with one creature you control (that you can see). This does not incur an attack of opportunity. This spell can be performed as a move action (takes up entire move action) or as a standard action.

Summoner's Curse. Necromancy Magic: Choose one creature that you control that is within 30 feet of you. Each time you take damage, all of the damage will be redirected to the selected creature (if the creature dies, any "leftover" damage does not carry over). This spell is automatically dispelled once the selected creature dies or if this spell is cast again by the same user.

Cursed Healing. Evocation Magic: You reduce your AC by X-amount to recover hit points (up to your maximum) by Xd12 plus your intelligence modifier. Example: if you reduce your AC by 3 then you recover hit points equal to 3d12 plus your intelligence modifier.

Sacrificial Armor. Necromancy Magic: Sacrifice one creature that you control within melee (5 feet) range of you and gain one AC.

Cursed Summoning (Details)

As a full-turn action you perform a quick ritual, sacrificing your own blood (hit points, cannot use temporary hit points) to summon monsters that obey your command. All summoned monster will spawn within a 10 feet radius of you and take their turn immediately after yours, however, they cannot attack on their first turn. The first time you cast this spell, start at Tier 1 and move up one tier for each additional time you cast this spell (does not have to be consecutive). You restart at Tier 1 as soon as all the currently summoned monsters that you control have been dispersed (killed, sacrificed, or otherwise removed) or after you attempt Tier 4 (failure or success). Each time you reset back to Tier 1 there is a 2 turn cool down (you must go through two entire turns before you can use this spell again).

(Tier 1) Pay 2 hit point and summon (2d4 + 1) poisonous snakes (CR 1/8 each)

(Tier 2) Pay 3 hit points and summon (1d4 + 1) skeletons (CR 1/4 each)

(Tier 3) Pay 6 hit points and sacrifice one creature you control (that you can see) to summon 1d2 (flip a coin) worgs (CR 1/2 each)

(Tier 4) Pay 9 hit points and sacrifice two skeletons (or one worg) that you control (that you can see) for a chance to summon a minotaur skeleton (CR 2 each) (roll a d20, no bonuses, DC 10)

Opportunity Attack. Volgroum controls a 5 feet "zone" in all directions around him. Whenever an opponent leaves his zone, Volgroum makes an opportunity attack (same as "Cursed Sword Attack" action) against them. Volgroum has no limits on the number of opportunity attacks he can make per turn (all other rules apply).