What's a good area in the game to get to use the Summon elements where the start of a battle starts with a blue or white line in order to get a head start on trying to use the right elements to get to use a Summon element?

Terra Tower is ok but its tricky to get used to. Chronopolis isn't too bad but I need to know of a good place to use the Yellow Field and Red field and Green Field elements

for being honest there arent truly many places where you can use elements its purley about luck, i recomend having level 1 elements of whatever color you wish, i found that ok, build up your gauge, now afterwards you must have at least 1 level of yellow alreday, use anything yellow, then make your partners do that if you are lucky you should have all the barriers AS one same color, now use teh summon, if im not mistaken also when figthing the dragons you can use esier the summon corresponding to them.