Cheapest priced copy (Reality Fracture Commander): $0.59 at Card Kingdom, near mint, their price list as of .
Windcrag Siege 
Enchantment · Rare · Tarkir: Dragonstorm Promos · #235p
As this enchantment enters, choose Mardu or Jeskai.
• Mardu — If a creature attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
• Jeskai — At the beginning of your upkeep, create a 1/1 red Goblin creature token. It gains lifelink and haste until end of turn.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
5 printings · $0.59 to $10.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Reality Fracture Commander | 52 | Rare | $0.59 | — |
| Tarkir: Dragonstorm Promos | 235p | Rare | $4.99 | $4.49 |
| Tarkir: Dragonstorm Promos | 235s | Rare | — | $5.99 |
| Tarkir: Dragonstorm | 235 | Rare | $2.99 | $4.49 |
| Tarkir: Dragonstorm | 392 | Rare | $4.49 | $10.99 |