Yagnoloth Arm

You infuse yourself or a willing creature with the abilities of a Yagnoloth, making only one of its arms grow in size and gain intensely disproportionate muscle mass. This massive arm can still be hidden behind clothing. The arm gains the following abilities:

• The arm counts as having a Strength score of 20 (+5) unless you already have this high of a score, in which it will count as a 24 (+7) instead. 
• Unarmed Strikes with the arm deal 3d12 + 4 bludgeoning damage. 
• When you successfully grapple a creature, you can for a bonus action, slam them to the ground, dealing 2d6 bludgeoning damage and knocking them prone