Bound Curse Mark

Warlock

Having made a trade with a suspicious demon in the depths of the Abyss, you trade power for power, this feature replaces your Hexblade's Curse class feature.   You may store an amount of curse-marks equal to your proficiency bonus, restoring 1 Curse mark whenever you roll a 1 or 20 on a 20-sided die or when you finish a long rest.
You can no longer land critical hits as normal, in exchange, as free action whenever you cast a spell or make an attack action you may spend an amount of Curse marks for one of the following effects.  

• 1 Curse mark: You may restore an amount of hit points equal to your proficiency bonus + spellcasting modifier.
• 2 Curse marks: your next valid weapon or spell attack always hits and becomes a critical hit. Critical hits created in this manner cannot be modified.