Vascular Memory

This spell siphons blood from a wounded creature, dealing 4d6 necrotic damage. The target must make a Constitution Saving Throw or lose its highest skill proficiency. This skill proficiency is granted to the caster. If the caster is already proficient in the skill, they double their proficiency for the duration of the spell. Once the spell is done, the caster loses the proficiency bonus and it is returned to the target.

At higher levels: When you cast this spell using a spell slot of 8th level, the duration extends to 24 hours, and when you cast it at 9th level the duration is extended until it is dispelled