First, get rid of shields all together. You want me to pay money to not play that game? Forget it. Sorry, D3, you are taking a cash hit here, but you will make it up for it and then some, see below. It sounds like you want to fix the shielding problems anyway.
Second, get rid of losing points for defensive losses (edit: and obviously remove getting points for defensive wins). It’s ‘player-versus-player’. I’m not playing, but I’m getting destroyed in points? It makes no sense. Without losing points on defense, teams won’t be forced to leave a defensive squad out and not play the game. They will use all the characters in their roster to get points and then start buying health packs. Risk takers will bring out 2* characters to beat a 3* team just to keep going. Yes, there is still a penalty for losing a battle. That’s what makes it exciting!
Third, the higher rank you are in PVP, the higher level your enemies will be. You are ranked 1st out of 500? Well congrats, every player you go up against will handicapped up to level 200+*. People will die more and spend money on health packs to play the game. People will start spending money on powerups to be able to take out seemingly impossible teams. Players will benefit from having large rosters to counter all the different enemies they might face. The best rosters and strategies will take players to victory. Pulling any random team in your event at powerful levels will stop the endless X-Force+Hood+whoever matchups and make every battle unique. Players will see an enemy before them and choose the best characters they have to counter them, not just run the same team out every few hours when a shield is up. Basically, players are rewarded for finding ways to win, not finding ways to hide and not play the game.
Finally, progression rewards are given for hitting scores calculated by total wins minus losses, not points. +100 wins gets you that sexy X-Force cover that you will love, but not need to use in every single battle. It won’t be a grind-fest because if you get wins, you get a high rank, then you to get harder battles. Basically, it all comes down to the best rosters, strategies, effort, and resources spent getting players the best rewards.
This is all off the top of my head. I’m sure we can find a way to tweak this to make a much more fun game. I would love to hear everyone else’s ideas. I know these are huge changes, but I think D3 can pull it off.
1, 2*, 3*, 4* teams do not scale equally well. Perhaps every enemy characters get scaled to max level + (25x the number of *'s the character has). The numbers will need to be tested, but looking at PVE data should give a rough idea. Maybe the number of points awarded for a win is based on the number of levels the opponent has in the fight?