Drain Life

You target a humanoid creature that has fallen to 0 hit points, dealing 3d6 necrotic damage to the target while they are vulnerable. You regain hit points equal to the damage dealt. You can use an action on your next turn and every subsequent turn thereafter to continue draining the target, repeating the initial roll you made when the target fell to 0 hit points. The spell ends early if the target stabilizes, regains consciousness, or when they die. If the target dies while this spell is active, the target can only be brought back to life with a true resurrection or wish spell due to the withering of their soul, and you increase your current and maximum hit points by 1d6. Your maximum hit points return to normal at the end of your next long rest.

At Higher Levels. The damage dealt by this spell increases by 1d6 for every 2 spell slot levels above 3rd level, as well as the amount by which you increase your current and maximum hit points.