Cheapest priced copy (Shadows over Innistrad): $0.49 at Card Kingdom, near mint, their price list as of .
Invocation of Saint Traft 
Enchantment — Aura · Rare · Shadows over Innistrad · #246
Enchant creature
Enchanted creature has "Whenever this creature attacks, create a 4/4 white Angel creature token with flying that's tapped and attacking. Exile that token at end of combat."
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shadows over Innistrad Promos | 246s | Rare | — | $0.69 |
| Shadows over Innistrad | 246 | Rare | $0.49 | $0.79 |
4 rulings from Wizards of the Coast
- 8 April 2016Removing Invocation of Saint Traft or the enchanted creature from the battlefield won’t stop the delayed triggered ability from exiling the Angel token at end of combat.
- 8 April 2016Although the token is attacking, it was never declared as an attacking creature (for purposes of abilities that trigger whenever a creature attacks, for example).
- 8 April 2016You declare which player or planeswalker the token is attacking as you put it onto the battlefield. It doesn’t have to be the same player or planeswalker the enchanted creature is attacking.
- 8 April 2016If an effect gives the token vigilance, the token will still enter the battlefield tapped.