Cheapest priced copy (Duel Decks: Zendikar vs. Eldrazi): $0.35 at Card Kingdom, near mint, their price list as of .
Repel the Darkness 
Instant · Common · Ultimate Masters · #29
Tap up to two target creatures.
Draw a card.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
4 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Zendikar vs. Eldrazi | 8 | Common | $0.35 | — |
| Foundations Jumpstart | 242 | Common | $0.35 | — |
| Rise of the Eldrazi | 42 | Common | $0.35 | $0.49 |
| Ultimate Masters | 29 | Common | $0.35 | $0.49 |
4 rulings from Wizards of the Coast
- 7 December 2018If you target one creature and that target is illegal as Repel the Darkness resolves, the spell doesn't resolve. You don't draw a card.
- 7 December 2018If you target two creatures and they're both illegal as Repel the Darkness resolves, the spell doesn't resolve; you don't draw a card. If just one target is illegal, the spell does resolve; the remaining legal target becomes tapped (if it's untapped at that time) and you draw a card.
- 7 December 2018You may target zero, one, or two creatures. The creatures don't need to be untapped.
- 7 December 2018If you target zero creatures, all that happens is you draw a card.