Chaos Sheath

You draw forth chaotic energy and ensorcell a non-magical melee weapon with it. For the duration, you can use your spellcasting ability instead of Strength or Dexterity for the attack; the weapons damage dice becomes 2d8, and the weapon becomes magical. 

Choose one of the d8s. The number rolled on that die determines the attack's damage type, as shown below.

If you roll the same number on both d8s, chaotic energy violently erupts from the weapon in the same direction as the initial target; Each creature within a 30ft long and 5ft wide line must make a Dexterity saving throw. A target takes 2d8 damage of the same type or half as much on a successful one.