Cheapest priced copy (Oath of the Gatewatch): $0.35 at Card Kingdom, near mint, their price list as of .
Embodiment of Insight 
Creature — Elemental · 4/4 · Uncommon · Oath of the Gatewatch · #131
Vigilance
Land creatures you control have vigilance.
Landfall — Whenever a land you control enters, you may have target land you control become a 3/3 Elemental creature with haste until end of turn. It's still a land.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Oath of the Gatewatch | 131 | Uncommon | $0.35 | $1.99 |
| Zendikar Rising Commander | 64 | Uncommon | $0.35 | — |
2 rulings from Wizards of the Coast
- 22 January 2016You may target a land that’s already a creature. For example, if you target a land that’s also a 0/0 creature and has three +1/+1 counters on it, the resulting land creature will be 6/6.
- 22 January 2016A “land creature” is a permanent that’s both a land and a creature.