You open yourself to the void and let the power of your master bleed into this plane. Squirming, ethereal, ebony tentacles - flecked with stars - erupt from a point of your choosing. They can fill a 20-foot square and for the duration, these tentacles turn the ground in the area into difficult terrain.
When a creature enters the affected area for the first time on a turn or starts its turn there, the creature must succeed on a Dexterity saving throw (DC17) or take 3d6 bludgeoning damage and be restrained by the tentacles until the spell ends. A creature that starts its turn in the area and is already restrained by the tentacles takes 3d6 bludgeoning damage.
A creature restrained by the tentacles can use its action to make a DC17 Strength or Dexterity check (it's choice). On a success, it frees itself.
If a creature dies by your tentacles you receive the final damage roll back as health.
The tentacles may also be scaled down and used for utility purposes.
* - (a piece of tentacle from a giant octopus or a giant squid)