Omnislash

You have mastered fighting with slashing weapons and using magic to make them even deadlier. If you are at least a 17th-level fighter and are wielding a magic melee weapon that deals slashing damage, you can use your action and both Action Surges to take the Attack action, targeting the same creature, in the same turn. You use your bonus action to focus the weapon's magic. You then take the Attack action, using the same magic melee weapon for each attack, followed by both Action Surges doing the same. Your attacks must target the same creature and all be with the same magic melee weapon that deals slashing damage. Afterwards, you suffer one level of exhaustion.