Cheapest priced copy (Fate Reforged): $0.35 at Card Kingdom, near mint, their price list as of .
Hunt the Weak 
Sorcery · Common · Kaladesh · #158
Put a +1/+1 counter on target creature you control. Then that creature fights target creature you don't control. (Each deals damage equal to its power to the other.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
7 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fate Reforged | 133 | Common | $0.35 | $0.49 |
| Iconic Masters | 167 | Common | $0.35 | $0.49 |
| Kaladesh | 158 | Common | $0.35 | $0.49 |
| Magic 2014 | 179 | Common | $0.35 | $0.49 |
| Magic 2015 | 179 | Common | $0.35 | $0.49 |
| The List | RIX-133 | Common | $0.35 | — |
| Rivals of Ixalan | 133 | Common | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 19 January 2018You can't cast Hunt the Weak unless you choose both a creature you control and a creature you don't control as targets.
- 19 January 2018If either target is an illegal target as Hunt the Weak resolves, neither creature will deal or be dealt damage.
- 19 January 2018If the creature you control is an illegal target as Hunt the Weak tries to resolve, you won't put a +1/+1 counter on it. If that creature is a legal target but the other creature isn't, you'll still put the counter on the creature you control.