Balance: New Rule:You can't trigger your own team's surprises. Surprises were designed to be fun reactive elements that disrupt the opponent's actions while they take their turn - not something to be used as a weapon on your own turn. That's why surprises are generally low mana cost, while spells that directly disrupt opponent casting, like Silence, cost a lot of mana and can be removed by healers. Some specific surprises, like Time Trap, could even create an undesirable "denial of turn" for their opponent by pushing/pulling their summoner into the trap without an opportunity to react against the trap being triggered. Note: There is one exception to this rule: Cards that revive a character as a surprise (Spirit Recall, Phylactery, Joker Potion) can still trigger on your own turn. These specific surprises are intended to protect you against unexpected deaths which can happen on your own turn, especially if triggered by another opponent's surprise, so I felt they kept in the spirit of the new rule.
Balance: New Rule:Cards cannot be discarded on your first turn. The aim of this change is to reduce rare, but possible, high impact first turn openers that can completely derail PvP games and provide a natural escalation to the battles. Some examples include: Discarding 2x cards to generate 1 extra mana and cast fireball (normally not affordable on player 1's first turn) on your opponent's team in the first turn when units are clustered together and then finishing off weaker guardians with your starting units' missile attacks. Second player discarding 2x cards to generate 1 extra mana and cast Mind Control on their opponent's favorite guardian on their first turn. The list goes on, but I think the aim speaks for itself: Give each player at least one turn to react, move into strategic positions, or cast defensive spells before the crazy shenanigans happen.
Balance: New Rule:Cards can now be recycled on the first turn after they've been replaced. The aim of this change is to further hedge against the RNG of a bad opening hand draw. This is important for both player and their opponent. If you're fighting an opponent with particular hard focus, you may need to find your specific counter. If you're playing as an opponent with a hard focus, you may need a specific card to get your strategy off the ground. This change only affects the first turn. You cannot replace cards twice, so trying to replace a card that's already been replaced will simply move it to the bottom of the deck so you have room to draw a new card at the end of your turn.
Balance: Meditate spell changes from "Draw a card. It costs 3 less. Receive Vulnerable (All 3) until start of their turn." to "Spend your action to get Vulnerable (All 3) until the start of your next turn when you choose 1 of 3 cards to cost 3 less." The prior implementation felt more like a better mana surge (the negative effect of which was easily counteracted by a healer). The new implementation creates a more thematic feel that creates better drama and reaction, especially in a PvP game. Previously, there was no reactive tempo to the drawn card (you got it immediately) but now the opponent can see your charging up and must now consider going forward with their previous plans or adapting their strategy.
Balance: Mating Season changes from "Cost 3: Draw up to 2 insectoid cards from your deck and add them to your hand. They cost 1 less." to "Cost 2: Draw up to 3 insectoid cards from your deck and add them to your hand." I decided to make the change because the synergy with Preserver (Insectoid cards cost 1 less) was resulting in a triple discount instead of a double discount, making this card too advantageous with the combo and nearly worthless without it. By changing the base Cost to 2, the card now has utility without the Preserver, allowing you to refill your hand and either pick from your best 3, discarding the other 2 for +1 mana. Or, when combined with Preserver, get a whole hand of cards you can cast at 1 cost discount by your next turn and providing your opponent a chance to react by dealing with the Preserver as a priority target. Math wise, the combined potential discount is reduced from a total discount potential of 5 mana at a cost of 3 to a discount potential of 4 at a cost of 2. Alternatively, you can discard 2 of the drawn cards for an extra mana to have the spell act like a mana surge on the preferred cast choice.
Balance: All cards that manipulate the deck by drawing cards to your hand or recovering from the discard pile now have the "Exile this card" rule. Exile takes the card out of play until end of battle. Previously, only Rejuvenate and Forbidden Library had this effect. Now it applies to Arcane Insight, Warp Time, Mating Season, and Resurgence as well. The utility of the cards is finding other specific, urgent need cards, so there isn't a good case to enable their direct recovery from the discard pile only to find/draw new instances of themselves.
Balance: Water Drake's life reduced from 8 to 7. This intended to help in both single player (specifically boss fight with Croakus) as well 2v2 PvP where the benefit of his ability greatly increases beyond this unit's casting cost.
Balance: Unusual Size changes from Surprise: "Give ally +2/+2 when attacked by an enemy on their turn. Small units get +4/+4." to "Give ally +2/+2 when targeted by an enemy. Small units get +4/+4." This allows the spell to be more versatile and work for spell damage as well as attacks and rebuffs.
Fixed Bug where Async MP victory Continue could cancel in-flight completeGame, leaving ranked matches stuck In Progress. (Thanks BEAST)
Async Multiplayer: Fixed bug where player names with non-Latin characters were not being displayed in the player panels. (Thanks Wesley)
Fixed Bug where lost Stage3D context during orientation could still throw a missing texture error when multiplayer hub game-option combo boxes rebuilt. (Thanks Guest_302952)
Fixed Bug where Error #3768 occurred on iOS when Stage3D uploads ran on background art / TextureLoader GPU while the app was deactivated. (Thanks potassium, B1GC, Corvid, Spruce)
Fixed Bug where Error #3768 occurred on iOS when Stage3D uploads ran on RankedMyStanding tier badges while the app was deactivated. (Thanks BEAST)
Build and release context
Steam update times within 24 hours of this post. Matching dates do not confirm which build it describes.