Text (TO+errata): 1/3. ; Discard a card: Switch ~this~'s power and toughness until end of turn. [Oracle 2005/08/01]
As per Rule 613, power and toughness switching is applied after any effects that modify power/toughness. This means that even if new spells and abilities are played to modify power/toughness, they are applied before the switch. [D'Angelo 2006/01/01]
Note - This card was creature type "Beast" until Oracle 2008/01/01, when it became "Elemental Beast".