Black Brier

Pitch black briers burst forth from your heart and wrap around a single arm of your choice, the thorns stabbing into your flesh. Thousands of black, thorny vines rocket out of the ground in a line towards a target. The vines completely ensnare the target and the briers thorns stick into it.

Sacrifice HP (one minimum, up to 4 at max), one creature of your choice is restrained and completely immobile for a number of your rounds equal to the amount of HP you sacrificed (the round you cast this spell does not count towards the total). The restrained creature cannot take any attack actions while the spell is active. The spell disperses once the designated number of rounds has passed. The creature also takes damage equal to the amount of HP you sacrificed once it is hit by the spell. You can still move and attack without change so long as the hand used to cast the spell remains free. All attacks against the restrained creature are rolled with advantage by anyone attempting an attack. A creature with a classification of Large or bigger can spend a turn and attempt to break free from the thorny briers. The creature must succeed against the caster in a strength contest (the creature must roll higher than the caster to escape). The spell ends once the designated amounts of turns is up (excluding the turn used to cast Black Brier) or the creature is killed.

(This spell can be cast with one hand. This spell does not impede movement, attacks, or concentration for the caster so long as the hand used to cast the spell remains free for the duration of the spell.)