[Morgeruat]

mine is teleport field, it's great watching a carefully set up group of enemies in a nearly impregnable wedge suddenly zip all over the map (no save), prevents swarming which can be deadly to any character, (esp ones with the attack script) and with boots of speed (paladin w/carsomyr, and ranger dual wielding- boots from the planar sphere and token machine from spellhold) you catch them before they can swarm you.

I also like glitterdust (reveal illusion and blind all in one)