Cheapest priced copy (Jumpstart 2022): $1.29 at Card Kingdom, near mint, their price list as of .
Goblin Rabblemaster 
Creature — Goblin Warrior · 2/2 · Rare · Magic 2015 · #145
Other Goblin creatures you control attack each combat if able.
At the beginning of combat on your turn, create a 1/1 red Goblin creature token with haste.
Whenever this creature attacks, it gets +1/+0 until end of turn for each other attacking Goblin.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
8 printings · $1.29 to $9.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Merfolk vs. Goblins | 46 | Rare | $1.49 | — |
| Jumpstart 2022 | 545 | Rare | $1.29 | — |
| Foundations Jumpstart | 558 | Rare | $1.29 | — |
| Magic 2015 | 145 | Rare | $1.79 | $3.99 |
| 30th Anniversary Play Promos | 22 | Rare | — | $1.49 |
| Magic 2015 Promos | 145 | Rare | — | $1.49 |
| Secret Lair Drop | 215 | Rare | $9.49 | $9.99 |
| Secret Lair Drop (Goblin Cradle-Thieves) | 2836 | Rare | — | — |
3 rulings from Wizards of the Coast
- 18 July 2014If, during your declare attackers step, a creature that must attack if able is tapped, is affected by a spell or ability that says it can't attack, or hasn't been under your control continuously since the turn began (and doesn't have haste), then it doesn't attack. If there's a cost associated with having a creature attack, you're not forced to pay that cost, so it doesn't have to attack in that case either.
- 18 July 2014The number of attacking Goblins is counted as the last ability resolves, and the bonus is locked in at that time.
- 18 July 2014Although Goblin Rabblemaster doesn't force itself to attack, if you control two of them, they'll force each other to attack if able.