Just practice, that's the key. Find/create a static group and practice. Even with 15% Echo buff if you can't dodge them, divebombs will kill you (or more precisely the wall will). Same goes for Twisters and the knights.
T5 being in DF now, a lot of people thinks it's as easy as the dungeons. But Coil is something else, you really need to work as a group there therefore finding 7 other players who you can play with is mandatory.

Moreover I would say, if you barely make it with 15%, practice some more. You don't have the Echo buff on T6+ and you will see the difference right away.