Cheapest priced copy (Commander Masters): $0.35 at Card Kingdom, near mint, their price list as of .
Shelter 
Instant · Common · Modern Horizons · #28
Target creature you control gains protection from the color of your choice until end of turn.
Draw a card.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
7 printings · $0.35 to $12.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 56 | Common | $0.35 | $0.79 |
| Eternal Masters | 29 | Common | $0.35 | $0.79 |
| Modern Horizons | 28 | Common | $0.35 | $1.99Out of stock |
| Odyssey | 46 | Common | $0.49 | $10.99 |
| The List | ODY-46 | Common | $0.35 | — |
| Secret Lair Drop | 1587 | Rare | $9.49 | — |
| Secret Lair Drop | 1587★ | Rare | — | $12.99 |
4 rulings from Wizards of the Coast
- 14 June 2019You can’t choose “artifact” or “colorless” as Shelter asks you to choose a color, since those are not colors.
- 14 June 2019Protection from a color means that the target creature can’t be blocked by creatures of that color, can’t be the target of spells of that color or abilities from sources of that color, can’t be enchanted or equipped by Auras or Equipment of that color, and all damage that sources of that color would deal to it is prevented. Nothing other than these events is prevented or illegal.
- 14 June 2019A permanent gaining protection may cause a spell or ability on the stack to have an illegal target. As a spell or ability tries to resolve, if all its targets are illegal, that spell or ability doesn’t resolve. None of its effects happen, including effects unrelated to the target. If at least one target is still legal, the spell or ability does as much as it can to the remaining legal targets, and its other effects still happen.
- 14 June 2019The legality of a spell’s targets is checked only as that spell begins to resolve. If Shelter gives the targeted creature protection from white, you’ll still draw a card.