There are 4 classes in Scarlet Fate: Warrior, Magician, Archer, and Knight 

Warrior: High DEF, high HP, and good ATK, usually placed at the front line (spot 1) to take DMG for their teammates 

Magician: Good at healing and AOE 

Archer: Can deal high DMG to a single target 

Knight: Good at healing and dodging, can offer additional buffs to boost the BP of the team 

How to switch the friends’ positions: Friends → Combat → Click the formation → Select the target to switch its position