I'm writing this at 09 December 2022. Before the card changes came out, and these are still not final, so anything can change later on. There were some changes in the off season "Base HP of NFT Axies increased from 320 → 400" This also means that non nft axies are starting on a lower hp, they removed a bunch of strength from free axies and they continue with that. The extra 80 hp generally helps defensive teams survive a bit longer. The fights also last a bit longer, at least early, since the energy changes. Harder to kill backline axies with targeted skills. Reduction runes and percentage damage/hp charms/runes are stronger, like leftover potion heals extra 4 hp, pangolin has more effective hp. It depends on card changes too, maybe just a bit of extrapolation.
"Return mechanic renamed to Keep. Cards are kept in Hand until the next turn instead of being put on top of the Draw Pile." The cards you click to keep, don't go back to the deck as before, mainly reduces the value of bug and plant and aqua cards, mainly 2x anemone, 2x leafbug and melon/papi, as they were healing you if drawn, now if you keep them it won't heal or apply shield. Also maybe better against blackmail, as it would replace the drawn card, so ruins your draw more, but now if you keep something, won't take away the space. Basically you had to pay an energy and a draw to return a card, now you only pay an energy and you get the same 5 draw slots.
'New game mechanic: "Energy Burst"' The energy was 1-2-3-3-… for the starting team, and 2-2-3-3-… for the second team, this didn't change, but there was more of a team build issue, if you started, you only got to attack once, and get less draw, but they can only use 2 energy twice, and you will start the 3 energy turn on 5th turn. This was changed a few times, so I think it was in a good spot. My idea was that I start vs offensive teams and go second against defensive teams, as they can kill me early if I let them start, and use all attack, but I got more choices to go around shields if they are a more defensive team. This changed now, and not for the better. First of all, first team needs 15 energy spent, and second needs 12 energy. The draws are 3-3-4-5-5... so a deck of 18 will repeat after 3,5 turns usually, then again 3-4 more, unless your axies die, or you got some banish-able or retain cards. This means you go 1+2+3+3+3+3=15, 6 turns to reach 15 energy as a first team. 2+2+3+3+3=13 only 5 as second team. This also means that energy cards can and will hasten this cycle, the second team can use 2 energy to gain the burst energy earlier than the first team. The first team needs 3 energy to speed up the process, regardless will use 12 energy with 12 cards that cost energy, which going first is 5 turns, and if the 3 other come from boost, then 3 extra card, so 4 for 15 and 3 boost is exactly 18 cards, so best case 5 turns. Second team has a draw, and now can keep an extra card too, before only first team could hold. So needs luck to pull the 2 energy cards but it's possible to get 10 energy in 4 turns and 2 for the boost in one more. Most of the cards that give energy, also thin the deck, eventually, once the confuse from the unstable is pulled (or banish charm on it) so it's possible to really hasten up the process with cards that give energy and don't go away (kotaro only out of the 6 energy cards). The other case is Goda, where you destroy one energy, sending a void into opponents deck, and that has a medium chance to be pulled by the opponent, since it will come after the rotation, the first two rotations are 7 turns in a normal case, and 5-6 turns to get energy for the boost. so it will trigger usually, before they finish the boost, or a turn later if they are lucky. While second team can lose a single energy and still complete the boost the same time. The value of disabling cards is also higher, doubletalk, tinyturtle and kestrel can disable an axie and can disable the cards they can use. However you can still spend an energy to keep the cards and push the boost meter higher. Retain cards can't be kept, not sure if this is a new change, there wasn't much of value in this until now, but with this, it might be an issue, drawing too many, as you got to use it just to boost energy and not to keep for value.
So clearly going second is better, you got a turn advantage to get the boost energy, you got one less energy to spend or you can waste one and still do it on time. There are cases where holding a card is better than attacking, but you can keep the card by spending the energy, even if it's retained by default. And you can see this now, most teams try to go second all the time, and you actually have to play rock/paper/scrisors to go second now.
"Blood Moon mechanic reworked" This is also a weird one, now axies don't lose hp in blood moon, but lose the maximum hp, which only deals damage if they are over that hp. This also means that having hp charms is stronger, as you can use curses or shields to survive long enough for the opponent to die. Mainly the plant mythic rune and charms that give hp. Poison and backline/random/aoe attacks got worse because of this, since it pressured teams from two treats, and finished off axies if they didn't heal. Other weird thing is the ravens tactic and the beast rune, that require 50% or 75% hp for additional effects, since your max hp goes lower, they can go from inactive to active again even without healing. These might be changed so I need to take a look on the new runes, but they are still usable right now. Also makes AOE stronger in some way, since leaving a low hp target on the backline alive can bite you in the long run, bubbles or feathers or guru rune is the only way to deal damage to them consistently. The poison nerf was targeted, but still, those teams got slightly higher hp usually so you still die to them.
"Class Potential Points now scale linearly with Class Purity" The pure axies still got the same 15 points, but special classes can use their class purity as a neutral point, and each class card they got worth 1 more, so impure axies have comparably high potential points, 14 total, and you can use the points with neutral charms, so using multiple leftover class points to mix and match and use a charm. It also needs a specific order to equip your charms to use a neutral charm with your main class points then the rest with another, as normally would take the leftover points for those. I'm not a big fan of fully pure axies, so I think it's good change. You still won't be able to use too many high value charms, but at least mixed axies can use neutral charms for higher total value.
"Neutral charms can be equipped with mixed Potential Points"
As I said, before this, you could only use your remaining points to equip low cost charms for each point, now you can mix and match your leftover points and equip higher cost charms, but only if it's neutral, you still need full points to equip class charms.
"Secrets can no longer be dispelled. Only removed by effects such as [Arco]'s" Both arco and oranda triggered the draw from pumpkin and bone sail, before removing it, not usre on other cards.
On the explanation site, it says that impure axies get 14 pp now. source https://axie.notion.site/Season-2-Mechanics-Explained-d4de883ade4b49448c2b9789e004fc8f