Cheapest priced copy (Dragons of Tarkir): $0.35 at Card Kingdom, near mint, their price list as of .
Glaring Aegis 
Enchantment — Aura · Common · Core Set 2020 · #18
Enchant creature
When this Aura enters, tap target creature an opponent controls.
Enchanted creature gets +1/+3.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dragons of Tarkir | 18 | Common | $0.35 | $0.49 |
| Core Set 2020 | 18 | Common | $0.35 | $0.49 |
| The List | DTK-18 | Common | $0.35 | — |
One ruling from Wizards of the Coast
- 12 July 2019If the target creature is an illegal target by the time Glaring Aegis tries to resolve, the spell doesn't resolve. It won't enter the battlefield, so its ability won't trigger.