Cheapest priced copy (Forgotten Realms Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Shielding Plax 
Enchantment — Aura · Common · Ultimate Masters · #222
({G/U} can be paid with either {G} or {U}.)
Enchant creature
When this Aura enters, draw a card.
Enchanted creature can't be the target of spells or abilities your opponents control.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
3 printings · $0.35 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Forgotten Realms Commander | 192 | Common | $0.35 | — |
| Dissension | 147 | Common | $0.35 | $1.99 |
| Ultimate Masters | 222 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 15 April 2013This is not the same as hexproof. If, for example, you target one of your opponent's creatures, your opponents won't be able to target their own creature with spells or abilities.
- 7 December 2018If the target creature is an illegal target by the time Shielding Plax tries to resolve, the Aura spell doesn't resolve. It won't enter the battlefield, so its enters-the-battlefield ability won't trigger.