The Ant Lion is the first monster you face after departing from the Will-o-Wisp Academy. It ambushes you on Erd after using Lassi's Wild Wind Magic to calm a raging sandstorm and allow you to continue. Some consider it to be the first boss you have to face, but it could generally agreed upon as a mini-boss instead.
It has two known attacks, Tail Swipe and Sand Blast. Tail Swipe focuses on one character while Sand Blast hits both characters.
Expect a level-up from both characters after this battle.