Disrupting Weapon

[Valix Bloodlord]

If I cast "Disrupting Weapon" on a +3 Greatsword and I attack an incorperal creature (A ghost) How many times do I have to roll a 50% miss-chance ? Before I have the creature roll a will save to avoid distruction ?

[Plausible Pseudonym]

You don't have a 50% miss chance when using magical weapons against incorporeal creatures, you do 50% damage.