UR Tears to Tiara Kakan no Daichi ティアーズ・トゥ・ティアラ Portable 42 NG+ Devil Mode Max Level Story Battles Continued 4 and Story Character Skill Books Upgrade & Equip plus Octavia Base Max Level 199 Sneak Peak

This battle is quite hard for a Minimal Leveling Run to make use of the later characters (Until Octavia, as you won't be using Taleshin in the last set of battles) for this you need to have rare equips on Morgan and have at least 25 Skill Level so she can use her Water Special Skill on the Left archer that can 1-Hit KO Octavia depending on the level differences (And since her Skill Books and Equipment are set even if you level Morgan's skill and exp up she has space for more skill books). She can learn her spells, though, when you level Morgan and still have a mid chance of evading the Boss's attack.