Hexagoth Tentacle

"“An indescribable feeling descends down the length of your arm, as though the very bones are thickening beneath your skin. As you watch, the flesh becomes taught, ash-white with the tension, before finally rending to make way for the slick dark material that emerges from beneath. You give your new arm an experimental flex as the last chunks of flesh sluice away from the bone, finding it strong and hard beyond belief. Hard enough, it appears, to even deflect bullets if used defensively.” —In-game description"

Effects

 * Mega Knockback on Melee
 * -40 Stamina