Cheapest priced copy (Fate Reforged): $0.49 at Card Kingdom, near mint, their price list as of .
Dromoka, the Eternal 
Legendary Creature — Dragon · 5/5 · Rare · Fate Reforged · #151
Flying
Whenever a Dragon you control attacks, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $2.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2017 | 170 | Rare | $0.59 | — |
| Magic Origins Clash Pack | 4 | Rare | — | $1.79 |
| Fate Reforged | 151 | Rare | $0.49 | $0.49 |
| Fate Reforged Promos | 151s | Rare | — | $2.29 |
3 rulings from Wizards of the Coast
- 24 November 2014You determine which creature to put counters on as the spell or ability that instructs you to bolster resolves.
- 24 November 2014Bolster itself doesn’t target any creature, though some spells and abilities that bolster may have other effects that target creatures. For example, you could put counters on a creature with protection from white with Abzan Skycaptain’s bolster ability.
- 24 November 2014Each Dragon you attack with will cause Dromoka’s triggered ability to trigger. For each instance of the ability, you’ll determine which creature to put +1/+1 counters on as it resolves. Specifically, the creature you control with the lowest toughness as the first such ability resolves may not have the lowest toughness as the second such ability resolves.