Theoretical CDR Mantra Spam Support Monk Build 2.1

Cooldown Reduction/Itemization Table
Armor/Weapon Name Cdr Value Diminishing Return Value
Helm Leoric's Crown 0.25 0.75
Shoulders N/A 0.08 0.92
Chest Born's 0 1
Gloves N/A 0.08 0.92
Bracers Strongarm Bracers 0 1
Belt Vigilante Belt 0.08 0.92
Pants Captain's 0 1
Boots Captain's 0 1
Ring 1 RORG 0.08 0.92
Ring 2 Band of Rue Chambers 0.08 0.92
Amulet N/A 0.08 0.92
Weapon 1 Born's 0.1 0.9
Weapon 2 N/A 0.1 0.9
Born's Set Bonus N/A 0.1 0.9
Captain's Set Bonus N/A 0.1 0.9
Paragon Points N/A 0.1 0.9
Beacon of Ytar N/A 0.2 0.8

diminishing returns calculation:  0.21482

total cooldown reduction:           0.78517

cdr priority: leoric's crown > beacon of ytar > weapons = set bonuses = paragon points > everything else

The way cdr is calculated follows this formula:

   CDR = 1 - [ (1 - CDR1) * (1 - CDR2) * (1 - CDR3) ]

So basically, you want to prioritize larger values of cdr over lower values of cdr to mitigate the effects of diminishing returns. 

Rough framework of skills:

   crippling wave: tsunami 
   cyclone strike: implosion
   epiphany: desert shroud
   inner sanctuary: forbidden palace
   mantra of healing: time of need
   serenity: ascension
   beacon of ytar
   sixth sense

Legendary Gem Choices:

   Gogok of Swiftness

Remember this is more of a concept than anything else. The build revolves around the skill serenity with the ascension rune which gives invulnerability to damage and movement impairments. The item choices allow for about 98% up-time of the skill. The other two percent are addressed with inner sanctuary and epiphany. Implosion is used to group monsters together (+30% damage buff from strongarms) and crippling wave is used for it's aoe freeze. Two weapons are used in conjunction with the Goguk of Swiftness legendary gem and the alacrity passive to ensure both spirit regeneration and freeze procs off of crippling wave.  (additionally, Goguk of Swiftness will provide an additional 15% cooldown reduction at rank 25)

Extra spirit generated will be used to spam the time of need mantra which provides a shield for both you and your allies. (This can be further combined with the sunwuko shoulders, amulet, and gloves to also get the holy proc and slightly different itemization) I left a lot of room for build variations so feel free to customized it to your own needs.  And hopefully, this was at least slightly insightful.    - Newsn31