Bloodied Freak

Bloodied Resilience: Even though its flesh has long decayed, this skeleton’s bones are stained with the blood of countless battles, granting it unnatural toughness. When the bloodied skeleton takes damage that would reduce it to 0 hit points, it can instead drop to 1 hit point once per day, fueled by its lingering will to fight.

Spellcasting. The Bloodied Skeleton is a 3rd-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 13, +5 to hit with spell attacks). The Bloodied Skeleton has the following wizard spells prepared: 

Black blood (1st-level necromancy)

Casting Time: 1 action
Range: Self
Components: V, S
Duration:  1 minute

You transform a portion of your blood into a poisonous substance. As you cast this spell, you must expend a number of hit points between 1 and 10. You gain temporary hit points equal to the amount expended. While these temporary hit points last, whenever a creature hits you with a melee attack within 5 feet, that creature becomes poisoned for 1 minute. A poisoned creature must succeed on a constitution saving throw at the end of each of its turns or take 1d6 poison damage. On a success, the poisoned condition ends.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, you gain 1d4 additional temporary hit points for each slot level above 1st.

Blackest Blood (1st-level necromancy)

Casting Time: 1 Reaction
Range: Self
Components: V, S
Duration:  1 minute

After taking damage, you can bend magic to weaponize your spilled blood. Any creatures within 5 feet of you when you take damage must make a Dexterity saving throw (DC = 8 + proficiency bonus + Charisma modifier), taking 2d6 necrotic damage on a failed save, or half damage on a success.

As an action, you can move the spilled blood (centered on you when the damage was taken) up to 30 feet. The blood can make a melee spell attack against a creature within 5 feet of it, dealing 2d6 necrotic damage. This effect lasts for up to 1 minute or until the blood has dealt total damage equal to the damage you initially took.

Blade of Blood (1st-level necromancy)

Casting Time: 1 bonus action
Range: Self
Components: V, S
Duration:  3 minutes

When you cast this spell on an ally’s weapon, that weapon’s attacks deal an additional 1d6 necrotic damage. If you take 5 points of damage before each attack, you can increase the extra damage to 3d6 necrotic damage for that attack. 

Blood lash: The bloodied skeleton lashes out with a whip-like tendril of cursed blood. Make a melee spell attack against one creature within 10 feet. On a hit, the target takes 1d8 necrotic damage and must succeed on a constitution saving throw (DC 13) or become poisoned until the end of its next turn.

If the target is already poisoned, it takes an additional 1d8 necrotic damage.

Black blood Spit. Ranged Weapon Attack: +5 to hit, range 30/60 ft., one target.
Hit: 10 (2d8 + 1) poison damage, and the target must succeed on a DC 13 Constitution saving throw or be poisoned until the end of its next turn. On a failed save, the black blood splatters onto the ground in a 5-foot radius around the target, creating a hazardous zone. Any creature that starts its turn in the zone must make a DC 13 Constitution saving throw or take 3 (1d6) poison damage.

Blood Ward: The bloodied skeleton uses its bonus action to harden the cursed blood coursing through its bones, gaining a protective barrier. Until the start of its next turn, it gains temporary hit points equal to 1d8 + its Constitution modifier.

Goreburst: When the bloodied skeleton takes damage from a melee attack, it can use its reaction to release a sudden burst of tainted blood. The attacker must succeed on a DC 13 Dexterity saving throw or take 2d6 necrotic damage and be pushed 5 feet away from the skeleton.