I went 4-0 with this deck on Friday and I've since made a couple of changes to become this.
+1 Angel of Serenity
-1 Azorius Charm
-1 Entreat the Angels
This deck is basically a UW Control deck splashing for a few cards.
Thragtusk is such a beating against a lot of decks in the format. It comes down, gains you life, and blocks two things. Late game you can just use Feeling of Dread to tap down their blocker and hit them for 5 a couple of times. It's such a versatile card and I think any deck that isn't aiming for a turn 5 kill should be playing 4 Thragtusk.
Each win condition (that isn't Thragtusk) has its own benefits and flaws that make them all good and make me want them all in my deck.
Entreat the Angels is super powerful and probably will win the game when you untap with it, but is the most vulnerable.
Sigarda is really hard to kill, but slow and doesn't impact the board. At 5, it also does a halfway decent Thragtusk impression to come down and block something.
Angel of Serenity impacts the board incredibly and gives you insane amounts of card advantage, but still just dies to a Dread Bore. It's also 2 more mana than Sigarda.
Any thoughts are welcome.
There's a lot of synergy between Rewind and card:Sphinx's Revelation you might want to consider. Being able to still counter whatever your opponent plays and retain mana for the Card draw/life gain with the Revelations is great. Is there any advantage to Thought Scour other than the one mana cost drawing? I don't see anything that would benefit you if they had more stuff in their graveyard. Inaction Injunction is a decent card if you're just looking to filter your deck.
I just came back to magic for Return to Ravnica, but I did play quite a bit during the original ravnica and timespiral blocks. Anyway here's a deck that might interest you Standard U/W Control. It's based off of the dralnu du lovre decks that were played during the timespiral set. I'm sure how people have played and such has shifted since then, but as someone who loves permissive control I love adding in counter spells.
Btw here's my rendition of the Dralnu decks Dralnu Du Pickles