Great concept that's programmed by chimps. It'd be like someone traveled back in time to make WoW with people programming out of their garage, i.e. the game concept would still be great but it'd look pretty unpolished. The first hour or so is just horrible because you literally have no idea what you're doing and the tutorial doesn't explain jack. But once you get used to it, it's quite awesome. It plays more like a RPG than a puzzle game honestly. You really have to think about how to attack the other team and the PvE guys have very different strengths/weaknesses. For the PvP stuff, people tend to have either the same cookie cutter team, or it's the 3 highest guys they could level. I came in around #12 on the two tournaments I entered but getting the push to #10 is very tough (that's where the big prizes are).
Some random stuff that might be useful to you:
Your heal packs do not regenerate until it's under 5 (at 36m per one), so unless you're making a huge push to a tournament there's no reason to have heal packs above 4.
Black Widow is very good PvE unless you got lucky and have Spiderman (classic). She's also decent in PvP against any team that has only one particularly strong character and no AE character (e.g. Classic Storm). You only need her blue ability. She can even be level 1 and still stun stuff for 5 turns (if they don't AE).
In the tournaments with the loaned character, try to let the loaned character take all the damage because he heals up for free between fights.
The buff modifiers modifies environmental damage and crit modifier. In practical terms this means in a PvP tournament you should always fight in the computer room (top choice) against a significantly stronger team, and always fight in city (bottom right) if your team is significantly stronger. This is because computer room environmental tiles can completely dominate the outcome of a fight, so you want to use that if you're the underdog, and conversely city has the weakest environment effects so if you're ahead. The forest tile (bottom left) is pretty well-balanced. It obviously favors red players which describes roughly half of the characters so it's pretty even.
One strong hero is way better than 3 weak ones.
Thor and Classic Storm are probably the best 2 star heroes to spend your iso-8s on. They both have covers you can actually get, and Thor is featured in many tournament as a buffed hero. Classic Storm is generally considered one of the strongest characters overall (though not as strong as she used to be), though keep in mind Classic Storm is useless on PvP on defense. She pretty much always dies first unless you have Spiderman, who is a rare (3 star).
Some random stuff that might be useful to you:
Your heal packs do not regenerate until it's under 5 (at 36m per one), so unless you're making a huge push to a tournament there's no reason to have heal packs above 4.
Black Widow is very good PvE unless you got lucky and have Spiderman (classic). She's also decent in PvP against any team that has only one particularly strong character and no AE character (e.g. Classic Storm). You only need her blue ability. She can even be level 1 and still stun stuff for 5 turns (if they don't AE).
In the tournaments with the loaned character, try to let the loaned character take all the damage because he heals up for free between fights.
The buff modifiers modifies environmental damage and crit modifier. In practical terms this means in a PvP tournament you should always fight in the computer room (top choice) against a significantly stronger team, and always fight in city (bottom right) if your team is significantly stronger. This is because computer room environmental tiles can completely dominate the outcome of a fight, so you want to use that if you're the underdog, and conversely city has the weakest environment effects so if you're ahead. The forest tile (bottom left) is pretty well-balanced. It obviously favors red players which describes roughly half of the characters so it's pretty even.
One strong hero is way better than 3 weak ones.
Thor and Classic Storm are probably the best 2 star heroes to spend your iso-8s on. They both have covers you can actually get, and Thor is featured in many tournament as a buffed hero. Classic Storm is generally considered one of the strongest characters overall (though not as strong as she used to be), though keep in mind Classic Storm is useless on PvP on defense. She pretty much always dies first unless you have Spiderman, who is a rare (3 star).