Twin-Blade Mastery

You've mastered fighting with double-bladed weapons, using both ends to devastating effect. You gain the following benefits:

• While you are wielding a double weapon with which you are proficient, whenever you roll the maximum on a weapon damage die against a creature, you gain a +1 bonus to the next attack roll you make against that creature before the end of your next turn.
• You can engage in Double-Weapon Fighting even when the weapon you are wielding lacks the light property.
• Before you make a melee weapon attack while wielding a double weapon in two hands, you can choose to forgo your proficiency bonus. If the attack hits, you add one and a half times your proficiency bonus to the attack's damage.
• Before you make a melee weapon attack while wielding a double weapon in one hand, you can choose to forgo your proficiency bonus. If the attack hits, you add your proficiency bonus to the attack's damage.