Rin will help greatly with hell's flame actually. Use weapon rend, dusk elegy, hex of darkness, and dark seed then seal it off with curse of strings. Curse of strings doesn't disable and
DoT magic already cast onn the enemy, plus Rin will allow you to effectively use Blessing of life 2 times in one turn when you don't have the ap. Also princess order is only okay-ish, beating sun helps alot

. Plus if you have witch with your exo, you can destroy enemy
MP so they can't use empress or other melee/range magic. I'm a staff main and I use it effectively in
PvP 
. The exo will also heal and add
AP to your staff users with speed cast and also once the
MP is gone from empress, use mana seal to stop enemy monk, then there is no magical protection on enemy form

Believe or not, seal staff is also pretty decent, it deals alot of
DoT to staff user, so you cud potentially use weapon rend, hell's flame, seal staff, and then curse of strings to intensely hinder the abilities of the annoying staff users like elementalist on the enemy form, and b/c they can't be healed u cud also potentially attack the staff with inventor/sheriff 3 times on the same turn with Rin:P I also don't use brutal will very often, b/c I'm staff main, witch and mwindo are super fun in tbs, after the initial turn of meteor/flame blow/primal monsoon, all mobs are either dead, will die on their next turn from the fires made, or can be finished off with cata. Beating sun I'm sure helps alot with the bosses as well since they can't use magic, they can only either kill witch or mwindo, allowing you to use a turn to pot up for more healing. Aswell for your form, I would trade minst for mwindo, that way you can disable 2 enemy mercs magic on enemy front row with 2x beating sun. In
PvP you will most likely not be using flame blow and just healing so vamp not super needed if you get rin, but druid will help with rin+inv/sheriff. Rin is also good for anti requiem should your monk die if you can empty out enemy mana pools, they can't pot up with sheriff attacking so much

Valk could replace mwindo in
PvP too, then use quickening or odins chain with the hells flame, weapon rend, seal staff or curse of strings combo. I've written a lot hehe I'll let someone else have a turn
