Apologies for the late reply.
Regarding gear, most of the game it was the already mentioned Grave Calling + Kitchen Stove combo. Kitchen Stove's special is great, its Thunderous Report with monk Int has a huge cone, deals high damage and debuffs foes with Daze for a long time. And of course, instant Ascension. I like having a Priest with Salvation of Time to extend its duration.
With Seeker's Fang taking over after Seeker, Slayer, Survivor (Spider Flurry has a far smaller cone, but its often possible to get 3 enemies in it... and it's devastating - while also instantly filling your Focus) .
Other notable stuff: Helm of the White Void (+10 Accuracy is awesome - and you take advantage of it all the time with Stunning Surge/Forbidden Fist or the Cipher debuffs/CC).
Devil of Caroc Breastplate is awesome for nearly every character, offering a good balance of speed and protection, bonus immunities and bonus resources. But not exactly critical here.
Abilities... Parting Sorrow is important for monks, particularly FF. Stunning Blows+Surge, Swift Strikes+Flurry, Duality+Turning Wheel, Thunderous Blows, Heartbeat Drumming, Two Weapon Style. If you have the slots, Crucible of Suffering is very nice also... and Rooting Pain. Also Improved Critical (with Community Patch). Flagellant's Path was already mentioned, I liked it a lot, but I guess it depends on play style (and PL VI slots are kinda sparse).
On the Cipher side, Borrowed Instinct, Disintegration, Secret Horrors, Ectopsychic Echo, Mental Binding. Amplified Wave can be strong vs mobs. Hammering Thoughts are a good passive. Draining Whip, of course. The Empty Soul is great. Whispers of Treason and Puppet Master can be situationally very good (and kinda staple for a Cipher), I liked Ring Leader less (short range, makes combat more chaotic, many enemies can quickly flip from Charm). I also like Mind Plague a lot, its a strong debuff. Situationally also Eyestrike. Recall Agony and Psychovampiric Shield are strong vs bosses. Echoing Horror can be nice - but not exactly critical.