Dark Augmentation.  Xavier has a +5 bonus to his Strength, Dexterity, and Constitution saving throws plus an additional 5 ft. of walking speed.

Duel Wielder. Xavier adds a +1 bonus to AC while he is wielding a separate melee weapon in each hand, can use two-weapon fighting even when the one-handed melee weapons he is wielding aren't light, and can draw or stow two one-handed weapons when he would normally be able to draw or stow only one.

Two-Weapon Fighting. While duel-wielding each weapon can be swung in a single attack action. Each weapon is rolled separately to hit and for damage. The off-hand weapon's damage doesn't add the Str/Dex mod.

Fey Ancestry. Xavier has advantage on saving throws against being charmed, and magic can’t put him to sleep.

Marshal Undead. Unless Xavier is incapacitated, it and undead creatures of its choice within 60 feet of it have advantage on saving throws against features that turn undead.

Blood Maledict (3/Short Rest). Xavier can invoke a blood curse a number of times per short rest. Before it affects the target, Xavier can choose to amplify the curse. An amplified curse gains an additional effect noted in the curse's description. Amplifying a curse causes Xavier to take 1d8 points of necrotic damage that cannot be reduced in any way. Creatures that don't have blood in their bodies are immune to blood curses, unless the curse has been amplified.

• Hemocraft Die - 1d8

Brand of Castigation (1/Short Rest). Xavier always knows the direction of the branded creature as long as it’s on the same plane as him. Each time the branded creature deals damage to Xavier or another creature he can see within 5 ft. of himself, the branded creature takes 10 psychic damage. Xavier's brand lasts until he dismisses it or until he applies a brand to another creature. His brand can be dispelled with dispel magic and is treated as a level 7 spell.

• Brand of Axiom. Any illusions disguising or making a creature invisible when Xavier brands them ends, and they can’t benefit from such illusions while branded. If a creature branded by him is polymorphed or has changed shape, they must succeed on a (DC 18) WIS saving throw or revert to their true form and be stunned until the end of Xavier's next turn. Whenever a branded creature attempts to polymorph or change shape, they must succeed on a (DC 18) WIS saving throw or the attempt fails, and they are stunned until the end of Xavier's next turn.
• Brand of Tethering. Branded creatures can’t take the Dash action and if a creature branded by Xavier attempts to teleport or leave their current plane via ability, spell, or portal, they take 4d6 psychic damage and must make a WIS saving throw (DC 18). On a failure, the attempt to teleport or leave the plane fails.

Spellcasting. Xavier has access to two spells. His spellcasting ability is Intelligence (spell save DC 16, +10 to hit with spell attacks). He has the following spell prepared:

Cantrip (At-Will): booming blade

Multiattack. Xavier makes two attacks with either Adamantine Meteor or Vestige of Doom.

Adamantine Meteor. Melee or Ranged Weapon Attack: +12 to hit, reach 5 ft. or range 60/120 ft., one target. Hit: 11 (1d8 + 7) slashing bludgeoning damage.

• Extra 2d8 bludgeoning damage to objects.
• Extra 3d8 bludgeoning damage to celestials.
• Returning. While within 120 feet of Xavier and not in his hand, the warhammer's chain can be pulled as a bonus action and causes the weapon to teleport back into his open hand.

Vestige of Doom. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 11 (1d8 + 7) bludgeoning damage.

• Double damage to objects and structures.
• (2/Long Rest) earth tremor (DC 16 Dex).
• Xavier can make a Bonus Action attack after hitiing with Vestige of Doom.

Blood Curses.

Corrosion. a creature within 30 ft. of Xavier becomes poisoned. At the end of each of its turns, the target can make a CON saving throw (DC 18) to end the curse.

• Amplify. The cursed creature takes 4d6 necrotic damage, and takes this damage every time it fails its CON saving throw to end the curse.

Binding. Xavier attempts to bind a Large or smaller creature that he can see within 30 ft. of himself. It must succeed on a STR Saving Throw (DC 18) or the cursed creature’s speed is reduced to 0 and it cannot take reactions until the end of Xavier's next turn.

• Amplify. The curse lasts for 1 minute and affects creatures of any size. The cursed creature can repeat the saving throw at the end of each of its turns to end the curse.

Marked. Xavier marks a creature that he can see within 30 feet of himself. Until the end of Xavier's turn, whenever he hits the cursed creature with a weapon for which he has an active crimson rite, he rolls an additional hemocraft die (1d8) when determining the extra damage from the rite.

• Amplify. The next attack roll Xavier makes against the target before the end of his turn has advantage.

Muddled Mind. Xavier curses a creature he can see within 30 ft. of himself that is concentrating on a spell or a feature that requires concentration. The cursed target has disadvantage on the next CON saving throw it makes to maintain concentration before the end of Xavier's next turn.

• Amplify. The cursed creature has disadvantage on all CON saving throws made to maintain concentration until the end of Xavier's next turn.

Crimson Rite. Xavier imbues a weapon to strike for 1d8 extra damage of his chosen type. On activating the rite, he takes 1d8 damage. Rite damage is magical and lasts while you hold the weapon or until you complete a short/long rest.

• Oracle. Psychic damage.
• Dead. Necrotic damage.
• Frozen. Cold damage.

Mutagencraft (3/Short Rest).

• Potency. Xavier's Str score increases by 4, as does his maximum for that score. However, he has disadvantage on Dex saving throws.
• Cruelty. When Xavier uses the Attack action, he can make one weapon attack as a bonus action. However, he has disadvantage on INT, WIS, and CHA saving throws.
• Gelid. Xavier has resistance to cold damage and vulnerability to fire damage.
• Precision. Xavier's weapon attacks score a critical hit when he rolls a 19 or 20. However, he has disadvantage on STR saving throws.
• Rapidity. Xavier's speed increases by 15 ft. However, he has disadvantage on Intelligence checks.
• Shielded. Xavier has resistance to slashing damage, and he has vulnerability to bludgeoning damage.
• Vermillion. Xavier gains an additional use of his Blood Maledict feature. However, he have disadvantage on death saving throws.

Strange Metabolism (1/Long Rest). Trigger's a burst of adrenaline that lets Xavier temporarily resist the negative effects of a mutagen. He can ignore the negative side effect of one mutagen affecting him for 1 minute.

Blood Curses.

Fallen Puppet. When a creature Xavier can see within 30 ft. drops to 0 HP, he can use his reaction to have that creature make one weapon attack against a target of his choice within its range.

• Amplify. Xavier can first cause the cursed creature to move up to half its speed, and grant a +5 bonus to its attack roll.