Bloodlord

After four days of hiking, the thief began to vibrate. Then, he exploded. the other adventurers looked around, only to find a cloaked figure with a crimson staff. They all felt their bodies stiffen, as their vision went black...

Bloodcurdle

When a creature you can see takes piercing, bludgeoning, or slashing damage, you may use your reaction to temporarily freeze their blood. They must succeed on a constitution saving throw against your spell save DC, or succumb to the effects of their blood freezing. Until the beginning of your next turn, the target may only take only an action, a bonus action, or move, and they cannot take reactions. You may use this feature a number of times equal to your proficiency bonus. You regain all expended uses of this feature when you finish a long rest.

first to draw blood

Whenever someone you can see takes piercing, bludgeoning, or slashing damage for the first time in combat, you may use bloodcurdle without expending a use of the feature. You use that twice per long rest. Whenever someone within five feet of you takes piercing, bludgeoning, or slashing damage, you may use your reaction to regain hit points equal the amount of damage they took. The hit points regained can only be regained from one attack on a turn. For example, someone with the extra attack feature does two attacks. You use this feature to regain hit points from only the first attack. You may use this feature a number of times equal to twice your charisma modifier (minimum of twice).

Blood mastery

When you use bloodcurdle, any creature of a challenge rating of three or lower does not require you to expend a use of that feature. If the creature has a challenge rating of three or lower, you may extend the duration of the feature to a minute. When you use bloodcurdle on a creature, you may expend a spell slot to make the duration of bloodcurdle round equal to the slot level. additionally, any creature under the effect of bloodcurdle takes 1d6 necrotic damage at the beginning of each of their turns. If you used a spell slot, the damage becomes 1d12 instead. The creature does not take damage at the beginning of their turn if you say otherwise.

A brutal ending

Alas, the blood lord has finally given you full blood control. Whenever you can see your own blood, you may control it as if you were casting the control water spell. Additionally, whenever a creature you can see meets the requirements for you to use bloodcurdle, you may instead use your reaction to manipulate the blood within their body. The creature must succeed on a constitution save against your spell save DC, or implode and immediately die. If they succeed, they instead take 10d10 necrotic damage. You may use this feature once in between long rests, unless you expend 2 warlock spell slots to do so.