Your first battle with Cynder starts right after you defeat the Electric King. After defeating him go through the door and a commander will show up, casting a spell on 6 different spots around the room. After defeating him smash those six points to keep going. Step onto the elevator to et to the next level- you'll have to battle enemies as you go up. When you reach the next floor you'll have to defeat some more soldiers/ cmmanders and unblock the elevator again. This pattern goes for about 4 floors in all. Once you reach the top you'll be battling Cynder for the first time.