Questioner wrote:I read a post about this by lord art,which got me to think.Is this accomplished by actually cutting them off from energy?(in which case you cant do anything intill the omnimancer lets you) or is it more of a technique you can defend against?
In effect it's like cutting them off from energy (but does more, like negating their magical senses). And "cutting off" isn't really how it works. The issue comes from a way of doing it that doesn't hurt them, but stops them from being able to do anything. Not that this is how it works, but it might be like a nerve strike in martial arts, where they hit you in a spot and your arm goes limp. You are ok, but you can't move your arm.
Can you defend against it? Depends if your defenses can stop a spell affecting you. And if they can, can they hold up against what might be used to remove or bypass those defenses? If they can't, I think you have your answer.
While i am at it,what is sparring?Are the participants projecting?or are you just thinking at each other?
Omni sparring is projecting. It's safest and for what is learned, it doesn't matter if one projected or not to use what is learned. In other systems, you'd have to ask them.