Cool Encounter #3

On a plane where the PCs are transmuted to 60' tall(naked, Hut roofes make OK shields), They encounter a Xaos elemental (Looks like a black tornado with bodies, gravestones and debris sucked up into it, very low AC, moderate HP) It can only be hurt by hitting it three times in a row with the third attack from same source (right fist, tree trunk), third try does damage