Cheapest priced copy (Legions): $0.35 at Card Kingdom, near mint, their price list as of .
Warbreak Trumpeter 
Creature — Goblin · 1/1 · Uncommon · Legions · #116
Morph {X}{X}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When this creature is turned face up, create X 1/1 red Goblin creature tokens.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.35 to $4.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Legions | 116 | Uncommon | $0.35 | $4.49 |
2 rulings from Wizards of the Coast
- 4 October 2004The trigger occurs when you use the Morph ability to turn the card face up, or when an effect turns it face up. It will not trigger on being revealed or on leaving the battlefield.
- 4 October 2004The X in the ability has the same value as the X paid in the Morph ability. This is pretty easy to derive since there is no other source of X.