Planeswalkers are my favourite card-type by far, so I really wanted to make a deck focussed around them. As this is only for casual, it's not intended to be as optimal as possible (i.e. I'm not running Jace, the Mind Sculptor & Liliana of the Veil, as not only are they too powerful for casual, but they're very expensive also).
The deck will try and win through getting enough planeswalkers out that the opponent will have to let one ultimate get off. Ideally, I will get a turn 2 Fog Bank followed by a turn 3 Jace Beleren and a turn 4 walker - any of them are fine.
Vraska the Unseen is amazing with the board wipes, as she can ultimate the same turn I use a board wipe, and then the opponent has to get three creatures out the next turn or they lose. Kiora, the Crashing Wave is very nice for protecting my walkers too - especially if a Fog Bank is out also. Liliana Vess and Jace can together tutor a Supreme Verdict (Lily puts it on top of the deck, then Jace draws it), letting my blow up the field at will.
Rebuff the Wicked is here for protection. Whilst cards like Dissipate or Dissolve may be better in general, the main goal is to protect the planeswalkers, and 1 mana is a lot less than 3 to need to leave open! Garruk Wildspeaker helps on the mana front, and can help me use other two-of-the-same-colour walkers (as I can tap the same land twice).
I have thought about adding red, and swapping Elspeth, Knight-Errant for Ajani Vengeant, as Elspeth doesn't seem great in this deck (although she does have nice interaction with Vraska and Kiora's ultimates in her minus.) Sorin, Lord of Innistrad seems like it will suffer the same problem, but at least his ultimate is fantastic. Narset Transcendent is giving me a draw around half the time, which is pretty nice, and she doesn't look like she is doing much and her ultimate can come out of nowhere, which is nice.
Grim Affliction, Tezzeret's Gambit & Spread the Sickness are all there for proliferate, and when testing they seem to do a really good job of getting ultimates off quickly.
I haven't built this deck yet, due to the cost and availability of planeswalkers, but I already have the Jaces, and will probably buy the rest in January.
Edit: After thinking a bit, I decided to take out Elspeth and Lily and put in 4 Sylvan Caryatid, letting me switch lands a bit. Elspeth seemed to do-nothing in a walker deck, and Lily was too expensive and not making a big enough impact. Sylvan Caryatid will be good for mana ramping and fixing, I hope! I might try and make room for Ajani Steadfast, as his minus ability looks fun for getting ultimates off!
