Crystal Tower gear will also only be ilvl 80 if it is a tier lower than coil. If there's not enough gear between coil drops and myth gear then the fight is in fact broken/poorly tuned when even being almost at the ilvl of the instance a group still cannot down the final boss. It would be one thing if coil didn't drop items to fill almost every slot for every class but outside of the few pieces it doesn't seem to drop(or that no one has linked yet) it has the gear to fill almost all of those slots and then you can supliment the rest with myth gear. If CT gear in those last few slots is needed to down this boss then there's something else wrong with the boss(or group skill) considering the jump from DL to CT will only be about the same as AK to DL(which isn't a make or break a fight difference if it's only a select few slots).