At the North Crater go to the point where you split your party down the two paths. Send everyone but Cloud down the RIGHT PATH and tell Cloud to go left. When Clouds path divides choose the UPPER path. Go down it to where all three paths meet. DO NOT walk towards the stairway that leads further down. This would cause your party to appear and ruin the trick. Now go back up the crater by taking the entarance to the lower path up to where the LEFT and RIGHT paths split. Now go down the RIGHT path this time. Grab the 2nd Msytile. Now go all the way down to the end again this time walking down toward the stairs leading down causing your party to appear. When you talk to TIFA she should give you 3rd MYSTILE!!!!!!!!!