[Standard] UBW Control/Mill Beginner Here!

So the first thought I have here is that this deck is WAYYYYY too fragmented.  You really need to decide whether you're wanting to play control or whether you're wanting to play something else, as you're definitely torn between strategies at the moment.

1) If you're going control/mill - go U/B.  It gives you access to Ashiok and Jace for milling purposes, Aetherling as a backup plan, and a TON of counter and removal options.  The current build's only answer to anything on the board is either Voyage's End or Supreme Verdict - the latter being good, but only if it's in conjunction with other control elements.  Rethink the counters you have - I'm thinking Syncopate and Essence Scatter among others - Psychic Strike isn't exactly optimal in most instances.  Additionally, you can remove essentially your entire creature base as a control deck doesn't really want to have any creatures on the field unless they're digging or are essential to winning (so think Omenspeaker and Aetherling and nothing else).

Keep in mind that playing this strategy will take a LOT of discipline and practice.  You need to evaluate threats and figure out which ones need removal and which ones need countered - so as to be sure to keep all your options open.  You will spend most of your turns drawing, playing a land, and passing the turn.  Your goal is to literally grind out your wins - meaning there is a chance you'll be going to turns and drawing a fair amount of the time.

2) If you choose to go with a more creature oriented deck, something of a mid-range if you will.  Then you can easily go U/W and include every single one of the creatures you're using (although I think 4x Daxos is a bit overkill as they'll often be dead cards in your hand).  Again, you'll want some responses for threats that actually hit the field, given that you'll frequently be tapped out from playing your own creatures, but that's not the hardest thing in the world given the removal that white has.  But keep in mind, all the planeswalkers you currently have in the build would have to go.

This type of deck is typically a bit easier to play as you're not really as focused on what they're doing at all times, instead acting with a bit more of a plan on your own.

3) Several cards I'm seeing here REALLY just aren't very good or just don't fit.  For instance, Mind Grind.  Sure, you can mill them for a bunch, but that doesn't really accomplish much if they're landing threats on the board and beating your face in.  You typically want to keep counter mana up and the sorcery speed of it is completely counter to that idea.  Next, Immortal Servitude... to get you what?  Reanimate the Omenspeakers following a Supreme Verdict? - Keep in mind that you would end up likely scrying the same few cards over and over again.

I'm also not really seeing why Thassa is in here as a 4x.  I get that she's powerful, cheapest of the gods, scrying every turn, getting things unblockable.  But having 4x not only costs a ton of cash, it will also result in numerous dead draws (or dead cards in hand), and given the current makeup of your deck, seldom ever will your devotion be high enough to really start swinging with her.  She strikes me more as a 2x or 3x card and probably in a more blue devotion dedicated deck with things like Claustrophobia, Frostburn Weird and even potentially Master of Waves - a totally different deck than what you have here.

4) The mana... You'll probably notice that I've suggested two different paths, both in two colors.  Given the rotation of the check lands and the incomplete cycle of the Temples, playing three color is going to be sketchy in terms of color requirements.  It will take a full 12 set of the relevant shock-lands (that's roughly $120 there in just lands) to even have a chance of working properly.

So, the take away point here is that you need to choose between a control/mill type deck that has a LOT more focus on spot removal OR go with a more creature centric deck that can have fun with things like Daxos and possibly Thassa.