Nihil is basically the anti-form of magic. It will cancel magic out, through explosions or negation. But in offense and defense it will act like magic as well, just not spells, because spells are magic. So it can do, attacks, barriers, teleportation, etc. But like.. spell circles, curses, hexes, things that actually require incantation or will, to make an effect happen. That's a spell, and Nihil won't do.
Because it's anti-magic, AM Fields won't block it, until there's an anti-nihil field. This is good though, because you can use it to encase, like I did. Spirit Energy isn't the only thing that can encase magic, anything that AM Fields won't cut off, that's an energy can encase magic, that's the secret to getting around AM Fields. So just as Spirit Energy can do it, so can Nihil if you control it not to cancel out a certain magic signature. That way, Barrier of magic + Barrier of Nihil around barrier of magic = Protection from AM Field and attack at the same time.