Van Galen's Vorpal Strikes

You enchant a weapon you touch, which erupts with in arcane energy. The weapon sheds dim light within 30 feet. Attacks with the enchanted weapon deal an additional 1d12 force damage and score a critical hit on an 18, 19, or 20.

Once per round when you achieve a critical hit with the enchanted weapon, you may choose to either make one additional attack with the same weapon or, instead of dealing damage, shove or disarm the target (if appropriate).

As an action, you move up to your speed without provoking opportunity attacks and make 1 attack with advantage. For this attack, the bonus damage increases to 3d12 force damage. After this attack the spell ends.