But moving away from current news on this game and getting back to spec overviews:
Past:
Sirlin's hype link
Flavor:
Unique Mechanic: Fading, which is a direct rip of MtG's Fading keyword, but works differently in a small number of significant ways due to other rules differences in the games. The most key difference are that in Codex, all cards have ablative health and attacker chooses which defending units to attack (within the restrictions imposed by the patrol zone) thus in Codex the odds of any unit surviving more than 2-3 turns are much much lower than in MtG, and consequently Fading is a much less significant drawback in Codex than it is in MtG, where creatures fully heal each turn and the defender can choose not to block with them, making it far more significant that a Fading creature comes with a built in expiration date.
Rule Book (version 39), page 19
Fading
Arrives with X time runes. Remove one each upkeep.
When you remove the last, sacrifice this.
Rule Book (version 39), page 18
Whenever an effect doesn’t specify owner or controller, it means controller. Owner is so rare that we spell that out specifically when it’s needed. Things like “Your units get +1/+1” mean “units you control get +1/+1” not “units you OWN get +1/+1”.
Hero: Prynn Playtestwaslax
Hero Innates:
Her startband ability is just downside, with same edge case rules issue that all Fading cards have - if an opponent or a partner in 2-headed dragon mode uses an effect to remove the final time counter, then "you" never remove the final time counter and the card only fades if it somehow later acquires another time rune.
Her Midband is a serious case of WTFery., due mainly to "Dies from fading" not being explicitly defined and Rulings on the card since stuff went to the printer being outright contradictory.
Codex Online Card Rulings wrote:
2016-03-02: She fades away when her last time rune is removed for any reason. Removing the last rune with the Time Spiral spell or her own max level ability will cause her to die.
This is true for the standard rules, aside from the bit I mentioned above about the "you" on the card being a pointer which allows for teamplay trickery
2016-03-02: "Dies from fading" means that the last time rune she had was removed because the fading ability said to do that during the upkeep. It doesn't trigger if something else removed her last time rune.
If I use an effect which removes the last Time Rune from a card, then the only reasons anything at all would happen to that card are because the card has Fading or Forecast. If I somehow would have a Time Rune on a card which had neither of those Keywords, and then use an effect, to remove it nothing at all would happen. But if I do the exact same thing to a card with Fading, I have to sacrifice the card. But somehow doing so is not supposed to count as "dies from fading".
If that is the intended functionality, then the card should have been errata'ed to say "dies during upkeep" or something similar -- depending on which timing rules hairs you wanted to split for the ability. Or heck, changed it before the printers set it avoiding the need for errata. Since you know, that ruling was apparently made a day before the Kickstarter even closed.
2016-03-02: If she has exactly two time runes, she CAN use her max level ability to trash a unit. If she does, she then immediately dies from fading, then the trashed unit returns to play.
2016-03-02: When her max level ability returns a unit to play, it returns under the control of whoever controlled it when it was trashed.
2016-03-02: When her max level ability returns a unit to play, it returns in a "fresh" state. It's a new object, and no longer has any properties of the old object such as +1/+1 runes, damage, being a dance partner from Two Step, etc. It also returns ready (not exhausted) and it can't attack or use exhaust abilities unless it has haste.
Those don't expose additional rules issues, but note that it's yet another way for a monopurple deck to get an additional attack with a Hyperion.
Her maxband is a really useful removal ability that's only temporary, allowing for all sorts of clever trickery.
Spells
Vortoss Emblem: This is hyper niche, but it's zero cost.
Undo: it's Unsummon, save that it can't target Heroes nor Tech III units. It's also got the Bounce keyword -- which doesn't actually mean anything rules-wise. This isn't bad, but Past has other, better ways to do the same thing, so this gets to be pretty niche
Origin Story This is Unsummon, which can only target Heroes. For new players, this spell can inspire pants-crapping fear, since it effectively negates any gold spent on leveling that hero up and makes channeling or ultimate spell based plans super high risk to try against Past. For veteran players it's actually considered kind of so-so, since it costs $3 and a card to bounce a Hero which only cost your opponent $2 and no card to play, and a savvy opponent will weigh the risk of getting hit with Origin Story against the benefits of spending gold to level up any of their heroes
Ultimate Spell:
Rewind: This is one of the best sweep / board clearing spells in Codex. It only costs 4, and Prynn doesn't have to survive a turn at maxband before casting it. On the downside, it only clears units, and it floods opposing hands.
TECH I Units:
Seer: this unit is time rune manipulation, and as such is part of a combo that you will rarely use.
More relevant is the other Past I unit: Stewardess of the Undone: This is a the key part of the Monopurple rush plan. Her stats are decent, especially in conjunction with Battle Suits, but her arrival ability to unsummon a Tech 0 unit is massively better than initially thought. If you tech for a Stewardess or two in your first cycle, then you can drop them in your 2nd cycle, in which case each will remove a opposing chump
blocker patroller, allowing for Purple to claim tempo and board advantage with its own starter units (Nullcraft, Fading Argonaut) , and/or one of the decent stat Tech Is from Present (Argonaut) or Future (Gilded Glaxx). The drawback of ceding card advantage to the opponent is overcome by parleying the earlygame board / tempo advantage into a Hyperion multi-blitz in the following cycle.
Tech II Units:
Shimmer ray: This is cheap and flies, at the cost of fading fast, mitigated by the ability to discard cards to counteract fading. The only time you care is if you are taking Past to Tech III and have to answer opposing fliers that Prynn's spells and abilities can't stall against.
Yesterday's Yogurt
Oh wait, it's actually Yesterdays Golgort - whatever the hell a Golgort is. Anywho, this is both cheap and relatively big, at the cost of fading fast. On the upside, it counteracts its own fading by damaging opposing buildings. So if you have some board advantage, this can stick around a bit to press that advantage pretty hard.
Rememberer: The ability here lets you fetch your Tech III unit from your discard, meaning that you don't have to wait to cycle after drafting it in during your Tech Phase. That one or two turn advantage is huge, and any plan that Specs past is going to want to Tech at least one of these in for that reason alone.
Slow-Time Generator: This building is Codex's version of the Winter Orb. Except due to Codex's resource and cardflow schemes, it's quite a bit more niche. While limited gold production is probably an advantage for Past with its suite of cheap fading cards over most other specs -- it's a rare case where this is a bigger advantage than having another 6/4 body on the board. And that 6/4 Golgort also costs less gold. So this is primarily a card to have in play when setting up theoretical tactical puzzle situations and not a card you will often play in actual games.
Second Chances: Each turn, this upgrade returns the "first" of your units which leaves play from anything other than combat damage to play. This counteracts Fading, and is strong against black removal and red direct damage, it also combos well with Present's Temporal Distortion and Future's Omegacron (although you have to either build a Tech Lab or cheat the 'Cron into play there). It also has in-Spec synergy Rewind, letting you keep have your best unit immediately return to the board. Unfortunately, the obvious synergy this has with
Enters the Battlefield Arrives and
Leaves the Battlefield Leaves abilities are only useful for minor time rune manipulation tricks in-color and most out of color arrives effects being horrific long-shots that either only grant minor effects or are on a Tech III - and if you have Past the odds of you building a Tech Lab for an out-of-spec Tech III are vanishingly small -- because Past gets one of the best Tech IIIs in the game:
Tech III Unit:
Ebbflow Archon: It has fading 7, but you can immediately remove a time rune to unsummon an opposing unit or opposing hero. So if you're on defense, this shows up and proceeds to immediately bounce 5-7 opposing threats, depending whether it needs to also bounce itself now and if you need the huge body as a patroller.
If you're on offense, this shows up, waits one turn, then bounces all 5 opposing patrollers and swings for 11, then bounces itself so you can replay to have it untapped with max counters. The only things it even has a chance to lose to are invisible forces, otherwise untargetable forces, and forces with enough haste to win a damage race.
Overall it's notably better than most of the other Tech III options in the game in that it provides both lockdown if your ahead on board and significant reversal if you're behind on the board.