Scouting lets you inspect enemy classes and positions before battle. Improve the Scouting Corps to reveal more enemies; in the abyss, you can encounter a mutation that blocks scouting.
Prepare an expedition in "Tower" and open "Scouting Intel". Check the revealed enemies and the count of hidden foes, then press "Start Battle" to fight.
Read the intel while choosing a party for an unfamiliar floor or one that defeated you. Against enemies that target the back row, check your healer’s protection; against mutations, review the mercenaries and relics that counter them.