Aye, cloaking is a piece of cake, as long as you don't want it to waver a bit (which can also be faked). Transparency should do the trick, although in some cases (Alpha Channels) it won't work on every object in the same fashion... But do your cloaking in the Materials Lab, like Alderon and Mahray suggested... Explosions? Make some fireballs and animate them, and pick the ones you like best...!