Cheapest priced copy (Theros): $0.35 at Card Kingdom, near mint, their price list as of .
Agent of Horizons 
Creature — Human Rogue · 3/2 · Common · Theros · #148
{2}{U}: This creature can't be blocked this turn.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Theros | 148 | Common | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 15 September 2013Activating the ability of Agent of Horizons after it's been blocked won't change or undo the block.