You’ll first unlock the Eastern Mesa as a map option when you enter Great Crag. This will allow you to purchase it from Initium for 5,000 St. If you want to save the money, though, you can visit the Southern Mesa. Head to the (roughly) northeastern corner of the map and you’ll find a lookout spot that unlocks Eastern Mesa for free.

The party battles enemies on the Eastern Mesa of the Tabletop Mountains, an area in The Legend of Legacy.

Tabletop Mountains - Thunder Drake Trail - Enemies
  • Archwing
  • Coatl
  • Dire Wasp
  • Fire Whelp
  • Frost Whelp
  • Goblin Fighter
  • Goblin Shaman
  • Hornshell Brute
  • Nest Warden
  • Primal Thrasher
  • Rockskin Brute
  • Stickbug Sentinel
  • Thunder Whelp
While you’re wandering through this area you may see insect enemies sticking to the scenery. They won’t attack you unless you examine them first, which is nice - though if you do decide to fight, you’ll face large groups of the things. Proceed with caution.

There’s a split right at the entrance. If you take a right you can find a Sparkle after a short trip. To the north is a raised platform; you can find an Archwing Egg nest up here.

Garnet explores the Tabletop Mountains in The Legend of Legacy.

Take the western-most path to the north once you’ve explored everything else near the entrance. You’ll find a stone column with a bug attached. Fight and defeat said bug to make the column collapse, creating a path to the east.

Walk to the northeast corner of the map and you’ll find an Archwing Egg nest. South of here, through a small clearing, is a ramp beside a cluster of bushes. If you go up the ramp you may find a Sparkle near a shell. If you go south from the ramp instead you’ll find an ancient device that can activate a fire on the previous platform, eliminating some of the battles. Beside this device is a yellow platform that'll give you a Bone Amulet.

The path splits at the device. East of here is an Archwing Egg, and a dead end. If you go west you’ll find another column to topple. Cross it to the west and you’ll find a singing stone and a Whispering Shard. The shard contains the Cloud Armor charm. That's all for the Eastern Mesa.

The party battles a huge Thunder Drake on the Tabletop Mountains in The Legend of Legacy.

Thunder Drake

Once you sell the map for the Eastern Mesa, back in Initium, you'll create a chance for a large Thunder Drake to spawn on this map. The chance is small that it'll appear, and you'll need to explore the entire map to check, as it only appears on the southeastern rise. 

The Thunder Drake is quite powerful, with a Volt Breath attack to go along with its standard Bite - and it often uses both attacks in a single round. That said, it still isn't quite a boss-level foe, and with a good defense and some strong physical attacks you can bring this thing down.