High Alert

Each creature you control assigns combat damage equal to its toughness rather than its power.
Creatures you control can attack as though they didn't have defender.
{2}{W}{U}: Untap target creature.

The List

Ravnica Allegiance

High Alert’s first ability doesn’t actually change any creature’s power. It changes only the amount of combat damage it assigns. All other rules and effects that check power or toughness use the real values. For example, Titanic Brawl won’t cause a creature to fight with its toughness under High Alert.