Full Combo monks can definitely fit in Occult Impaction. I'd argue that skill is a must for all Monk builds but Asura, where you should pick between that and Sphere Throw as your normal leveling skill (and Sphere Throw is better in most situations with Renewal Mechanics for damage due to overall reduced physical defense to balance out substantially reduced normal attack damage at mid/high levels in 2nd and trans classes).
I'm actually making my Monk a combo monk, though I'm making my Champ, once Trans is released, an Asura / Spirit Champ, and prep it for a Knuckle Arrow Sura build (I rather prefer that skill).
A basic Combo Template:
http://irowiki.org/~...iangFborFbnqnak
Now with this you'll have 2 extra points as an Acolyte. These can be either used for level 10 Agi Up, or level 7 Heal and 1 Warp Portal, or 2 Warp Portal, or 8 Heal, or even Agi Down and Signum Crucis, or 2 Signum Crucis. It doesn't matter what you do, any usage of those two points will be beneficial in one way or another.
As a monk you'll have 13 extra points. This can be used for a variety of options:
1) Root 3 (for Occult Impaction usage) + Spiritual Cadence 5 + Fury 5
2) Root 3 + Spiritual Cadence 5 + Mental Strength 5 (for party leveling as a tank...if you have 40+ VIT I recommend some Mental Strength, under 40, not that worthwhile)
3) Root 3 + Spiritual Cadence 2 + Mental Strength 5 + Fury 3
4) Root 3 + Spiritual Cadence 2 + Mental Strength 3 + Fury 5 (this might be the better route for overall auto-attack damage + MS, since 3 is a decent length and MS has the same defense boost regardless of level)
5) Root 3 + Mental Strength 5 + Fury 5 (not recommended, as Spiritual Cadence is exceedingly useful if you're running low on SP, but then with 33+ INT, that may not be a huge issue...it's far more useful as a Spirit Monk).
Other combinations work out well.
Something to note though. The faster your Monk is, the harder it is to combo, due to downtimes between combo attacks shrinks a little. It's not a huge deal for a combo Champ, given the downtime between Glacial and Chain Crush is fixed, but with Quadruple + Thrust, it's agi based. I recommend either a total of 70 AGI and a cap of 80. No higher than 80 total AGI, unless your ping is under 100.