Onyx's Black Tenticle

Weapon Magical, Versatile(1d10) Rare (this item requires attunement)

When this weapon is unsheated, tentacles fill a 20-foot square on the ground around the sword and turn it into difficult terrain. When a creature enters the area for the first time or starts its turn there, it must pass a Dexterity save of a DC 15 or take 3d6 bludgeoning damage and be restrained until the spell ends. If it's already restrained by the tentacles, it takes 3d6 bludgeoning damage. The restrained creature can use its action to make a Strength or Dexterity check of its choice. On a success, it's freed. The wielder of this weapon is immune to any of it's effects. Additionally, Whenever a non-Evil Alligned character makes an attack with this weapon it receives 1d8 Psychic Damage.