I find that Jace is strongest when you lock the AI’s hand by draining mana and increasing the cost of the cards in hand such that even a cascade isn’t going to summon out the first card. In particular this works well with the third ability which can keep your opponent’s hand drained of mana and ensure they just about never get to play any card.
You will get to this point where the AI is feebly trying to charge up its first card which is already designated its best card to play but it can’t outstrip your mana drain and the cost increases.
It’s going to be slow so it won’t be suited for QB but it can work rather well for Story / Events.
If I had all the cards my ideal deck of this design would be:
Drowner of Hope
Thopter Spy Network
Shrine of the Forgotten Gods
Sunken Hollow
Prairie Stream
Sphinx’s Tutelage
Prism Array
Talent of the Telepath
Scatter to the Wind / Horribly Awry
Disperse / Clutch of Currents / Harbinger of Tides
Creatures
The first two cards are there because their combo effect disables your opponent’s creatures for the rest of the game. If you don’t have both, Thopter Spy Network alone still works with the rest of the deck as the support gives you a draw whenever your token creatures attack the enemy planeswalker, working with Sphinx’s Tutelage.
Otherwise, Disciple of the Ring is another Mythic that fits the theme. Down in rarity, you have Deepfathom Skulker (though it is cost prohibitive for a 4/4), Jori En and Fathom Feeder. There’s also Mizzium Meddler which should be considered purely for its mana efficiency rather than it’s negligible effect. Further down the rarity line you get the usual suspects such as Sigiled Starfish or Jhessian Thief.
Supports
The next three cards are there for mana gain. Jace’s mana gain isn’t as strong as the other blue planeswalkers so you need some way to compensate. I have to say Shrine of the Forgotten Gods is (sadly) rather crucial to making any of the original planeswalkers (except Nissa) competitive at high levels.
Sphinx’s Tutelage is key to increasing the costs of cards in the opponent’s hands. The deck has rather varied means of drawing (Prism Array, TotT) so you should not have to wait long to draw this into hand.
Prism Array for the draw, and to disable anything that gets through. Getting a landfall will increase the opponent’s first card cost by up to 6 mana. In the case of the opponent triggering a landfall, the draw triggers before the mana gain which means the cost increase from Tutelage will also trigger before the mana gain.
Talent of the Telepath is important to fetch the right cards: Sphinx’s Tutelage, your ramp supports, an emergency Disperse or Scatter to the Winds. Pretty much your entire deck except your creatures and Thopter Spy Network will be autocast by this spell and that is really good for setup.
You want to be discarding any unnecessary cards in hand so that you can keep drawing. You can potentially be increasing the mana cost by 10 if you landfall with Prism Array out and have a bonus draw from one of your creatures or Thopter Spy Network.
Spells
Scatter to the Wind is necessary to clear the mana built up on your opponent’s first card as otherwise one good cascade will undo all your good work. The other option is Jace’s third ability. 15 loyalty for Trap 9 is a fair cost for pretty great odds to drain your opponent of a lot of mana. Horribly Awry also works well enough if you are missing Scatter to the Wind because it is really the creatures which you want to prevent from being played. You can use Disperse to bounce-destroy any tokens that get summoned by spells or supports.
Disperse is there to bounce back anything that makes it through the gaps. Clutch of Currents is a costlier alternative that still maintains the autocast-ability from Talent of the Telepath. Harbinger of Tides is an alternative which is more in line with the deck theme but loses the benefit of fetching from Jace’s second ability and the autocast-ability from Talent of the Telepath. It worked well for me in the past but Disperse has been my go-to at least for QB because for QB you only really need that temporary tempo disruption. You can try and see which works better for you.
If there’s any card you don’t have or prefer not to have in the deck, there’s still Jace’s Sanctum as an alternative. Jace’s Sanctum + Sphinx’s Tutelage alone is 5 mana a turn which isn’t small. This used to be a terror back before planeswalker caps were raised to 60 (mana gains were capped at +2/+1/+1/+0/+0 or +3/+1/+1/+0/+0 at 50) and before all the new planeswalkers with increased mana gains.
The most important question though is why Jace instead of Kiora?
Imo Jace edges Kiora out on this build cause of his second and third ability. Sure Kiora has 6 loyalty to drain 6 mana but Jace has 15 loyalty to drain up to 54 mana. That actually matters when the mana cost of the opponent’s first card is greatly increased by Sphinx’s Tutelage.
The second ability is more when you urgently need Scatter to the Winds cause you cannot wait another turn to use Mind Sculpt. You have a 1/3 chance of getting the spell and another 1/3 chance of getting Talent and fetching a Scatter in your next three cards. You do lose this benefit if you use Harbinger of Tides instead of Disperse though.
Another minor reason is when you have enough planeswalkers, you can keep this deck configuration in Jace and keep Kiora (if you have her) in Quick Battle configuration rather than having to change her decklist when switching between events and QB.
What achievements is this deck good at getting?
It is most definitely slow, but it’s suited for hitting story achievements like finish the match in 25 rounds or more, or event achievements for casting a certain number of supports (if you don’t have Tezzeret yet). Arguably it might be a decent candidate for the kill 2 or less enemy creatures achievements but I don’t have Shrine and without it my setup is too slow to lock down the opponent early enough. But Thopter Spy Network + Drowner of Hope will disable enemy creatures once out to ensure that you need not kill again till the end of the match.
edit
I added in the alternatives of Clutch of Currents and Harbinger of Tides for Disperse.
Also added in the explanation for Horribly Awry which I forgot earlier.