You have a fun idea using Detain with Cloudshift (fun for you, not your foe lol) and a good closing idea with the angel plan. Why not brew something specific up and let us pick that apart?
I tried so hard to remove cards from that list, I got it down to 55 cards, i need to remove at least 15-18 I would say, here's what I'm looking at right now (let me know if I removed any cards I should have kept or kept any cards I should have removed; I know mostly my creatures and instants are too bloated)
Creatures:
1 Angel of Serenity
2 Bruna, Light of Alabaster
2 Isperia 's Skywatch (are these any good, they seem expensive for a 3/3 flyer even with the detain)
1 Azor's Elocutors
1 Soulsworn Spirit
1 Angel of Jubilation
1 Azorius Justicar
2 Runewing
1 Hover Barrier (maybe don't need?)
1 Latch Seeker (maybe unnecessary with detains?)
2 Lyev Skyknight
2 Tower Drake (not sure on these)
1 Stealer of Secrets
2 Fog Bank (maybe don't need?)
3 Azorius Arrester
1 Nephalia Smuggler
Instants:
1 Banishing Stroke
1 Azorius Charm
2 Dramatic Rescue (not sure on these with 4 cloudshifts)
1 Syncopate
2 Ghostly Flicker
2 Cancel
1 Cyclonic Rift
4 Cloudshift
1 Swift Justice (maybe unnecessary?)
2 Unsummon
1 Blustersquall
Sorcery:
1 Terminus
1 Supreme Verdict
2 Ghostform
1 Inaction Injunction (maybe I have better ways to detain? but I like the card drawing)
Enchantments:
1 Spirit Away
1 Tricks of the Trade (i like this for stealer of secrets, even though it'll be rare)
1 Arrest
2 Detention Sphere
Artifacts:
1 Conjurer's Closet (I love this idea, I can re-detain at the end of every turn)
1 Angelic Armaments
Lands:
1 Hallowed Fountain
1 Azorius Guildgate
This is sort of the best I can get to at the moment, not really sure what's unnecessary in this list. I got rid of a lot of stuff I thought I'd like (palisade giant, faerie impostor, keening apparition, hussar patrols, counter spells) but I think I did an okay job of what I've taken out so far.
Any advice would be greatly appreciated!