First:
Don't get the illusion that this deck is just a pile of crap! It's just a pile of Illusions.
And I call it Illusions althought it plays some creatures which are not Illusions, but only because there are not
enough other strong Illusions.

The main reason for me to build this deck is Jace's Phantasm, a new card for the pauper format. I did not go all in on
milling my opponent to pump it to a 5/5 as fast as possible, because a 5/5 flyer can still be killed too easily by
many decks. And so my only backup would be milling my opponent, which sounds a bad plan.
Instead I made a improved Illusion tribal deck with only a few mill spells, so my opponents will need much more
removal to deal with all my creatures. Especially Krovikan Mist can get another very strong win condition for this
deck. It often gets a 4/4 or 5/5 pretty fast.
Dream Stalker is more like a wall and can block very effective with its 1/5 body. It's nice to have often, because we
otherwise would be very vulnerable with our many 1/1's. It's although the reason i added 4 Spellstutter Sprite's,
because we can return them back to hand with our Dream Stalker's. The Halimar Depth's are other good alternative
targets for bouncing back to hand and to replay them.
Althought they are no Illusions too, we play 2 Stormbound Geist main. The main reason for this is, to make the deck
more resistent to mass removal. And edict's will bother us far less, too.
The other 2 blue allstar creatures in my list are 1 Ninja of the Deep Hours and 1 Mulldrifter, just because they
can generate so much card advantage.

Some tactics:
I would wait with my mill spells as long as i could, and only play it when we have a Jace's Phantasm on the board,
and it would bring our opponent to 10 cards in the graveyard. But in case you need another land or a good play for
next turn I would use the Though Scour at the end of their turn then if possible.
Note that they although can't just bolt your Jace's Phantasm when they already have 9 card in their graveyard.
It will first grow to a 5/5 before the bolt resolves, so they will survive.

We play 15 basic Islands for the untapped blue mana we often need, 2 Halimar Depths to look at and sort the top
3 cards of our library and 2 Haunted Fengraf's for returning creatures from the graveyard later in the game.
That's a total of 19 lands. That should be enough since most of our spells cost no more than 2 mana and we play
much cantrips and card filtering.
A good hand to start with would need 2 or 3 blue mana producing lands and some good creatures (more Krovikan Mist's,
less Dream Stalkers). Your goal is to reach around 4 mana, so you can cast something and still have a counter open
in best case. When you have a good one land hand it might be right to keep it, too. But I think you would need 2 or
more strong 1-drop creatures in this case (Phantasmal Bears or Jace's Phantasm's) and a Preordain or Ponder to search
for another land.
I think the matchups are quite good against Dimir Control decks, MBC, Izzet Blitz, Mono Blue and Izzet Delver and
Affinity (Dream Stalker blocks their 4/4's really good). I think it's ok against Stompy, Tron and RDW, and against
Hexproof we should have good sideboard cards to have a good chance, too. The worst matchup might be Elves, we
just lack removal, and they are too fast to counter everything. Although really hard are games against Burn and
Boros Monarch/Kitty.

The cards:

3-4 ofs:
Jace's Phantasm: Most of the time the strongest card in this deck. But our tactic is not to get it to a 5/5 as fast
as possible, just wait until our opponent plays his spells then help maybe a bit with our Thought Scours.
It might be a good idea to board it out after sideboarding when you expect your opponent brings in graveyard hate.
Krovikan Mist: The second really strong threat we have in our deck. If our opponent can't kill it, it will kill him soon.
Dream Stalker: Another Illusion creature. It's a hard to remove defensive creature with 1/5 power/toughness. As bonus
it pumps up our Krovikan Mist's and you can bounce back Spellstutter Sprite's or other things to use them again.
Phantasmal Bear: A 2/2 bear for only one mana. It can be a good threat sometimes for turn one, in other games it just
dies to your opponents Quirion Rangers.
Mothdust Changeling: Because there is a lack of other strong Illusions to play, I play with this Changeling instead.
It has synergy both with Krovikan Mist and Spellstutter Sprite, so I'm really liking it in this deck. Note that you
can tap your Phantasmal Bears to give it flying, because the tapping cost does not target.
Spellstutter Sprite: No Illusion but a counterspell on a 1/1 flyer is really good. Remember that your Mothdust
Changelings count as Faeries too.
Preordain: Really good card filtering cantrip.
Thought Scour: Our mill cantrip spell. We might need to target us self sometimes for example when playing a Halimar
Depths and finding only cards we don't want to have.

1-2 ofs:
Fathom Seer: We only play 1 of this creature because returning 2 Islands back to hand sets our available mana back so
much.
Stormbound Geist: It's a Spirit and no Illusion, as you might expect, but it's really strong against Delver decks and
decks with much removal, so we play 2 of them in our mainboard.
Mulldrifter: We might not always reach 5 mana to cast it without evoke, but when we draw it late in the game and it
resolves it means we are back in busine$$.
Ninja of the Deep Hours: The best value might be when we can ninja back a Spellstutter Sprite, but because we have so
much flyers there are many other ways to bring him into play and draw some cards with it.
Bonesplitter: We play it as a 1-of to boost our creatures, downside is we often want to use our mana for other things
in our first turns.
Counterspell: If our opponent decides to play things we don't like...
Ponder: I don't want to play 8 card selection cantrips, only 5. And I prefered Preordain over Ponder because you can
select single cards which you want to put on bottom of your library with Preordain, so it ended just as 1-of.
Deep Analysis: Can draw us 4 cards in 2 steps, althought if we play against a control player he would need to counter
it 2 times to counter the full spell.
Compelling Argument: A card that mills 5 cards, but we although can cycle it to draw a card when we don't need it.

Sideboard:
2 Aura Flux: Main Sideboard card to bring in against Hexproof.
2 Hydroblast: Super strong sideboard card against decks which play red.
2 Muddle the Mixture: Additional counterspells. Can althought tutor up cards like Krovikan Mist, Fathom Seer, etc.
2 Echoing Truth: Should be good against Tokens, Hexproof, other very aggressive decks.
1 Winds of Rebuke: Another bounce spell and additional instant mill for 2.
1 Exclude: Additional counter for creature heavy decks.
1 Pendulum of Patterns: Gives 3 life. I play this against decks with much direct burn spells, because I otherwise
have no way to gain life. Can be bounced with Dream Stalker for more value.
1 Spreading Seas: Very good against tron or karoo lands, or multicolor decks which don't play blue.
+2 Counterspell
+1 Deep Analysis

Matches:

Some matches with random opponents on XMage, played in fast forward and without commentary.
When you watch in best video quality you should be able to read the cards.

1. Against Izzet Blitz and Affinity
   https://www.youtube.com/watch?v=aDBkh-DKhQA
   (the most interesting video so far)

2. Against RG Madness and Izzet Control
   https://www.youtube.com/watch?v=HeMhwWQjXAM

3. Against Boros Monarch and Izzet Blitz
   https://www.youtube.com/watch?v=fmr2HCZ0GIw