@wiley It's been a while, you're probably more accurate than I was in remembering.

A third copy of Psionic Blast seems reasonable, which is weird to say. I was thinking the deck could use an extra land. I'll test with those concepts and the ones I had (extra Jace, extra Crucible)

My hope is to be comfortable enough with the list to take it to Champs this year, hoping to get more feedback going in this thread to make the list as tight as possible.

I saw this list floating around online and decided to give it a go for my local Vintage event I run at my store. I ran this list:

3 Pack Rat
1 Demonic Tutor
1 Time Walk
1 Toxic Deluge
2 Ashiok, Nightmare Weaver
2 Jace, the Mind Sculptor
4 Standstill
1 Black Lotus
1 Crucible of Worlds
1 Engineered Explosives
1 Mox Jet
1 Mox Sapphire
4 Force of Will
3 Mana Drain
3 Mental Misstep
2 Misdirection
2 Psionic Blast
2 Spell Snare
1 Ancestral Recall
1 Flusterstorm
1 Hurkyl's Recall
4 Mutavault
4 Underground Sea
4 Wasteland
3 Island
3 Misty Rainforest
1 Creeping Tar Pit
1 Library of Alexandria
1 Scalding Tarn
1 Strip Mine

Sideboard:
3 Grafdigger's Cage
2 Dismember
2 Energy Flux
2 Yixlid Jailer
1 Echoing Truth
1 Hurkyl's Recall
1 Mindbreak Trap
1 Nihil Spellbomb
1 Surgical Extraction
1 Toxic Deluge

We ran 5 rounds with 21 players.

Round 1 (Griselbrand Oath, 2-1)
G1: I keep a solid hand on the play with good counter magic and a Standstill, then proceed to flood out hard seeing 11 lands and very few spells despite drawing 3 extra cards and he casually Vault Keys me.
G2: I mull to six and lead with turn 1 Jace off a Lotus on the play, the game goes pretty long with me countering anything relevant that he plays and eventually beating him to death with two Pack Rats and a Mutavault.
G3: Interesting game, we both keep sevens and throw counterspells at eachother, he eventually manages to resolve a Show and Tell for Griselbrand but is low on life from Pack Rat attacks and can't draw. I Psionic Blast him to 3 during his end step and untap to play Jace and bounce his Griselbrand and attack for the win.

Round 2 (MUD 1-2)
G1: I keep a land light hand with 2 Underground Seas and decent spell selection. In the early turns he Wastelands me twice and I never manage to find another source of mana to crawl back out and die to a Lodestone Golem.
G2: On the play I lead with Lotus into Energy Flux, he conceeds a few turns later.
G3: He leads by trying to lock a turn one Trinisphere which I Force. We fight for a while and I end up a mana short every turn I try to cast Energy Flux and end up dead with a full grip and very little to do about it.

Round 3 (Burning Oath 2-0)
G1: We play casually for a few turns until I resolve a Standstill, he decides it is time to go for it and breaks my Standstill while I'm on 7 with a Library, so I have 11 cards in hand to fight with. Three Force of Wills was enough to win the fight and he loses to Pack Rats a few turns later.
G2: Similiar to game one, a big counterspell fight around turn 5 and he loses the fight and dies to Mutavault attacking with Pack Rat.

Round 4 (MUD 2-0)
G1: He thought he had kept a Workshop hand and didn't and ended up short on mana which wasn't helped by Misstep on his Sol Ring and Wasteland on his Ancient Tomb. Countermagic kept him out of the game while Pack Rat and Mutavault brought it home.
G2: He mulls to 4 and I keep with double Force and Pack Rat, he never really got to play.

Round 5 I intentionally draw with the guy who ended up winning the tournament who was playing BUG Fish

So I go 3-1-1 into the Top 8. In the Top 8 I played against my loss from the Swiss rounds and had severe issues with drawing mana sources. We had a really great game where I stole his Karn with Ashiok and started animating his Moxen but I end up losing anyway. I think in two games I drew six lands total.

My opinions on the deck so far:
The deck is very strong, Pack Rat is super aggressive and I was never sad to be playing it as my win condition.
The countermagic package is pretty solid and I felt it reliable outside of game one against MUD where I have several dead cards. The two Misdirections were wonderful in my matches against Oath.
Ashiok was too cute, I wanted something better every time I saw here. I didn't play against Fish or any of the more creature heavy decks in our meta so she may be better than I've been able to see. I spent the tournament wishing she were a Jace, or a second Crucible. Just something better.
Psionic Blast put in great work, it was much easier to cast than Hero's Downfall and did everything I wanted it to do. I killed creatures and planeswalkers as well as using it to pressure life totals. I still feel like there has to be a better card.

I enjoyed playing this deck a lot and will certainly be playing it again with some minor tweeks. Currently testing cutting Ashiok for a third Jace and a second Crucible. I really want a  better card in place of Psionic Blast but can't think of one without adding a third color and stretching the mana base too thin.

Thanks for reading my first long post on TMD and please leave any feedback or suggestions. I hope more people discover the joy of beating people with Pack Rat in Vintage.

My name is Josh Staples and I am a level 2 Magic judge from Durham, NC. I work full time at Atomic Empire in Durham where I schedule our larger Magic events (you can find top 8 lists from some of our Eternal Weekend events in the tournament reports section of TMD) and manage the front retail end. When I'm not working or playing Magic I am traveling the east coast judging Grand Prix and StarCityGames events, some of you may have seen me around.