The Archive of Esoteric Secrets
3-level Transmutation
A beam of sickly purple energy attaches itself to a creature
within range, draining their lifeforce. Make a ranged spell attack
against a creature that you can see within range. On a hit, the
target takes 2d8 necrotic damage and is linked by the syphoning
grasp.
At the start of each of the target creatures turns whilst the link
is attached, it must succeed on a Constitution saving throw, or
take an additional 2d6 necrotic damage, taking half on a
success.
Any necrotic damage dealt by this spell reduces the target
creature's hit point maximum by an amount equal to the damage
dealt. Additionally, this spell has no effect on constructs or
undead.
The tether is broken if its takes radiant damage greater than
your spellcaster level + the spell's level, or the target creature
starts its turn more that 60 feet away from the caster. Either
effects end the spell early.
At higher levels: When you cast this spell using a spell slot
of 4th level or higher, the initial damage of the spell increases by
1d8 per spell slot level expended above 3rd.