Cheapest priced copy (Commander 2015): $0.49 at Card Kingdom, near mint, their price list as of .
Victory's Herald 
Creature — Angel · 4/4 · Rare · Mirrodin Besieged · #18
Flying
Whenever this creature attacks, attacking creatures gain flying and lifelink until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2015 | 83 | Rare | $0.49 | — |
| Commander Anthology Volume II | 38 | Rare | $0.49 | — |
| Mirrodin Besieged | 18 | Rare | $0.49 | $0.79 |
| Welcome Deck 2017 | 6 | Rare | $0.49 | — |
2 rulings from Wizards of the Coast
- 1 June 2011Victory’s Herald also gains flying (which will likely be redundant) and lifelink if it’s still attacking when the ability resolves.
- 1 June 2011Even though the triggered ability affects only attacking creatures, the bonuses will remain for the rest of the turn.