Arrow of Life Drain

This arrow deals an extra 2d8 necrotic damage when
it hits a target, and you heal the same amount of hit points.
The target must succeed on a DC 11 Constitution
saving throw or its hit point maximum is reduced
by an amount equal to the damage taken. This
reduction lasts until the creature finishes a long rest.
The target dies if this effect reduces its hit point
maximum to 0.