Cheapest priced copy (Shards of Alara): $0.35 at Card Kingdom, near mint, their price list as of .
Mighty Emergence 
Enchantment · Uncommon · Shards of Alara · #137
Whenever a creature you control with power 5 or greater enters, you may put two +1/+1 counters on it.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shards of Alara | 137 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 1 October 2008The ability checks that creature's power only once: when that creature enters. The trigger checks a creature's initial power upon being put on the battlefield, so it will take into account counters that it enters with and static abilities that may give it a continuous power boost once it's on the battlefield (such as the one on Glorious Anthem). After the creature is already on the battlefield, boosting its power with a spell (such as Giant Growth), activated ability, or triggered ability won't allow this ability to trigger; it's too late by then. Once the ability triggers, it will resolve no matter what the creature's power may become while the ability is on the stack.