My build currently goes...

Boots of Lucidity
Ruby Sightstone
Shurelyas
Locket of the Iron Solari
Runic Bulwark

This gives me 41% cdr so I would be at the cap of 40% with the 6% from my Masteries but for the 6th item what should I get? I was thinking it would be good to get an early Kage's Lucky Pick and build it out of that... so if that is the case which item should I build it into?

There is Morrellonomicon which I feel could be good with Soraka's Q and I could just swap Lucidity boots for Merc Treads since it comes with 20% cdr, or should I get one of the Twin Shadows/Shard of True Ice items?

Then there is also Rylai's that lets me slow the enemies with my Q as well as giving me some nice health.

Warmogs.

Warmogs
Always Warmogs
edit: Shen'd

sunfire cape. when they see the fire they know you mean business

probably wards

CDR caps at 40%. Rylais is a good option for tankiness and utility. Shard of True Ice would be my other choice.

Warmogs, Rylais, Will of the Ancients, Void Staff, Sorc Shoes, and item of choice.
BATTLERAKAAAAAAAAAAAAAAAAAAAAAA

Armor like all hell. had a tryndy that focused me when i had frozen heart. Best day ever.

pink wards

Crucible or Zeke's depending on what your team is needing. Crucible if your ADC is getting jumped on and you need to save them (extra heal too is nice) Zeke's is great if you are running an ADC and 1-2 AD champions in your top, jungle or mid. The 20 extra damage is going to help take anything on the map and help with team fights, and 10% life steal is huge for an aura. That bumps anyone who has build life steal to 20%-26% rather than 10%-16%.

Not warmog's like people are saying, you have enough hp built and if you go the zeke's route you will get some more hp anyway. Also Lucidity is nice, but more often than not I find Merc, or tabi the better way to go.