Amputate

You coat your hand with vicious Osteomancy. Make a melee spell attack roll against a creature within range, on a hit you deal 10d8 slashing damage. In addition you rip off one of the creature's limbs (leg or arm or other similar appendage).
A creature is immune to this effect if it is immune to slashing damage, has legendary actions, or the GM decides that the creature is too big for its limbs to be cut off with this spell. Such a creature takes an additional 5d8 slashing damage instead.

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, the primary damage increases by 4d8, and the secondary damage by 2d8 for each slot level above 7th.