Scout

There are 3 standard kinds of gacha in game, called scouting. There is also frequently (always?) an additional Event Scout. Scouting is the main way to attain new units. You scout by clicking on the icon from the Main Screen.

Event Scout
This is a gacha that gives you a boosted chance to get a featured (usually new) unit. It costs 3 CS (Core Stones) per attempt, or can be done in blocks of 30 CS for 10 units. Here is a breakdown of rates:

Premium Scout
This is a gacha that gives you 30 piecese of a unit. As with Event Scouting above, it also costs 3 CS per attempt, or can be done in blocks of 30 CS for 10 units. Here is a breakdown of rates:

Ticket Scout
This is a gacha that gives you a unit using a different currency; tickets. These can be obtained from login bonues. It uses the same rates table as Premium Scout

Follow Scout
This is a fundamentally different gacha from the other three. Using FP (Follow Points), one of the more easy to acquire currencies in the game, you can attempt to get a variety of items useful to progression in the game. The items you can nab are: Character Piece x1 (each unit from Premium Scout available), MP x1000, MP x5000, 1★ Upgrade Material x1 (each of the 5 classes available), 1★ Upgrade Material x1 for Core Parts. You can get FP from map clears, mission clears, and raid boss kills. Additionally, you can do up to three free Follow Scout gachas a day, reseting at 0:00, 8:00, and 16:00 JST.