Cheapest priced copy (Khans of Tarkir): $0.35 at Card Kingdom, near mint, their price list as of .
Feat of Resistance 
Instant · Common · The List · #KTK-10
Put a +1/+1 counter on target creature you control. It gains protection from the color of your choice until end of turn. (It can't be blocked, targeted, dealt damage, enchanted, or equipped by anything of that color.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Khans of Tarkir | 10 | Common | $0.35 | $0.79 |
| Core Set 2021 | 19 | Common | $0.35 | $0.49 |
| The List | KTK-10 | Common | $0.35 | — |
One ruling from Wizards of the Coast
- 20 September 2014You choose the color as Feat of Resistance resolves.