Cheapest priced copy (Iconic Masters): $0.79 at Card Kingdom, near mint, their price list as of .
Assault Formation 
Enchantment · Rare · Dragons of Tarkir · #173
Each creature you control assigns combat damage equal to its toughness rather than its power.
{G}: Target creature with defender can attack this turn as though it didn't have defender.
{2}{G}: Creatures you control get +0/+1 until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
5 printings · $0.79 to $2.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dragons of Tarkir | 173 | Rare | $1.29 | $2.49 |
| Iconic Masters | 155 | Uncommon | $0.79 | $2.49 |
| Jumpstart | 378 | Rare | $0.79Out of stock | — |
| The List | IMA-155 | Uncommon | $0.79 | — |
| Tarkir: Dragonstorm Commander | 246 | Rare | $0.79 | — |
2 rulings from Wizards of the Coast
- 17 November 2017For example, a 2/3 creature will assign 3 combat damage rather than 2.
- 17 November 2017Assault Formation’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, Hunt the Weak won’t cause a creature to fight with its toughness.