Dark Transmogrification

You transform one of your arms into a writhing tentacle. You can use your new appendage to make a weapon attack with a reach of up to 10ft. You use your spellcasting ability modifier for that attack. The attack deals 2d8 + spellcasting ability modifier damage. On a hit, you may also make a grapple against that creature, using your spellcasting ability modifier for the grapple check. Any equipment held in or on the chosen arm can be dropped on the ground or merged with the tentacle.

At Higher Levels. When you cast this spell at 2nd level or higher, the damage increases by 1d8 for each slot above the first.