For the Portal animation, I added some "particles" (really just tiny objects) and had them spin around the building, much like the Summoner's animation. There are two rings of particles on the outside, spinning in opposite directions, and one ring inside the portal spinning on a different axis at twice the speed. The animation is 17 frames. I would have made it shorter, but that's the minimum that I could have for the middle ring to do two smooth revolutions.
I'm not going to texture it because I know there are many of you who could do it better, so have at it.
Edit: Fluffy, remember to upload your work somewhere when you're done so we can use it.