Cheapest priced copy (The List): $0.39 at Card Kingdom, near mint, their price list as of .
High Alert 
Enchantment · Uncommon · Ravnica Allegiance · #182
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.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.39 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | RNA-182 | Uncommon | $0.39 | — |
| Ravnica Allegiance | 182 | Uncommon | $0.49 | $3.49 |
One ruling from Wizards of the Coast
- 25 January 2019High 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.