Cleric, Level 4
Range: 0 (Caster only)
Duration: See below
While this spell is in effect, all creatures living, undead, or artificial are unable to make physical contact with the caster.
The spell lasts as long as the caster continues to chant, "Can't touch this!" and perform the requisite somatic gyrations.
(I know I probably should have saved this for April 1st, but that's SOOOOO far away...)