As a standard action, you can expend an unused spell slot to temporarily grant the effects of a weapon fusion to a weapon that you touch. When you activate this ability, choose from the following weapon fusions: flaming, frost, ghost killer, merciful, or shock. If you expend a spell slot of 4th, 5th, or 6th level, you gain the ability to choose either the corrosive or thundering fusion. The weapon gains the chosen fusion for a number of rounds equal to the level of the spell slot you expended. The weapon can’t gain a fusion it already has or one that can’t be applied to a weapon of its type, but this bonus fusion doesn’t count toward the maximum total level of fusions the weapon can have at once. You must have the empowered weapon magic hack to choose this magic hack.