Do you get cards from leveling up uniforms or did I read that wrong? My cards suck so it'd be nice to work on leveling up uniforms for their cards if thats true.
Can you get any card from the honor card chests or just a select few? I keep getting the same ones.
You get a few cards from leveling up Unis as part of the Legendary Battle. The most notable one is Loki #2 by leveling up the Thor Ragnarok Uni to Mythic. This is a great card, but if you dont have the Thor Uni it might not be worth chasing it this point, as the Thor Infinity War Uni is better overall.
You can get anything from honor card chests expect "P" cards. "P" cards are some of he better cards in the game, but only come from a few places. Sadly, the main sources of getting them is RNG card loot boxes, which is a bad way to spend crystal. The previously mentioned Loki #2 is a "P" card. There are some amazing "P" cards, but you will throw a lot of money at the game trying to get the best ones.
The good news is there is a lot of great cards to get as random drops for free - or for a really small amount of crystals (125) in the Shield Lab Item Shop. Cards also come from Dimension Rifts, but there is only a few good ones in my opinion, however you will need to constantly run Rifts to get cards to feed to better cards to rank them up to Mythic.
In my opinion some of the best non-P cards are:
Avengers #318 (Nebula Rift)
Groot #5 (Groot Rift)
Star Lord #2 (Yondu Rift)
Loki #17 (Loki Rift)
Shield #12 (Random Drop / Item Shop)
Punisher #60 (Random Drop / Item Shop)
Gwenpool #1 (Random Drop / Item Shop) - this is the best free card in the game IMO
If you get all of these cards, or even a portion of them to Mythic, and equip the ones best for you, some of the stats are not going to be perfect, and you will need to rank up another card to Mythic to combine it with the good card to try and get better stats. The stats to look out for are the attack based one - Physical/Energy/All Attack, Ignore Defense, Critical Rate/Damage. You will also want a decent amount of Cooldown Duration. Max HP is good too. Avoid "Resits" stats as much you can - but some will creep into even the best cards.
It is hard to get perfect cards, but with enough luck, and months worth of rerolls, you should get 5 good ones that significantly help your roster.