User blog comment:BellatrixTheMagicalPotato/Why Voldemort Would Easily Kill Vader/@comment-4840996-20150603093720/@comment-26531114-20150608142122

1) Yes,Voldy wouldn't know. But Voldy is a Legilimens, therefore he would be able to penetrate Vader's mind, thus getting basic knowledge of the force and Vader's abilities.

2)No, Vader isn't dumb. But there are spells which look quite similar. Voldy would cast a simple color spell, which would look similar to Avada Kedavra. The first spell would be harmless, and Vader would assume the same curse would hit him, but it would turn out to be avada kedavra.

3) The beam may be made of light, but the shaft isn't. Therefore, reducto could easily destroy it.