Each creature assigns combat damage equal to its toughness rather than its power.
1/10/2007: Doran’s ability means, for example, that a 2/3 creature will assign 3 damage in combat instead of 2.
1/10/2007: Doran’s ability doesn’t actually change creatures’ power; it changes only the value of the combat damage they assign. All other rules and effects that check power or toughness use the real values.
1/10/2007: This effect is mandatory and affects all creatures.