I haven't played the game much, winter came, so it became too cold to play.As the first comment mentions. Expensive potions shouldn't be part of PvP.
I think it's better that there are some cheaper PvP potions that gives you different stats, and you can only use one offensive+defensive potion at a time, but they have lesser of an effect.
I think there should be a "prep" time where you select the deck you want, and apply potions, before the fight starts (PvP potions run out after a fight). I don't have any fancy gear, but I assume they're just small stat differences.
Set bonuses are bad, integrate those values into the pieces instead.
More varied bonuses and pretty big bonuses would be ideal. This includes things like:
"adds 5% damage/effect/heal of X spell" or "adds 2.5% damage/effect/heal of X category of spell",
"Increases time available to cast by 1 second" or "Decreases your opponents time to cast by 1 second (maximum 3 seocnds)",
"Reflects 2% of damage taken to opponent", "Converts 2% of damage dealt to HP", "adds a shield of X, refreshes every turn",
"Chance to apply a DoT upon damage dealt" or "Chance to apply a DoT upon damage recieved" or "Chance to apply a HoT upon damage dealt" or "Chance to apply a HoT upon damage recieved",
"Increases amount of heat by 1 (with a max value)" or "x% chance to drain heat from opponent upon dealing damage" or "x% chance to ignore/reduce heat cost upon spell cast"
"Ignores x/x% of armor stats of opponent" or "Increases your armor stats by x%" or "Increases your offensive equipment stats by x%"
Accompanied with regular stat bonuses.
All of these effects stacks, so the values need to be fairly small, or have max limits.
Quality of life:
Make level up bonuses to either be able to apply later on, once you're on Wifi, or to store up watched commercials prior to leveling up (through a currency). Watching commercials costs a lot of data, it's really not very convenient to be asked to watch a commercial when you're on mobile data.
Be able to walk in an area, and later on pickup the items you were in range of, and fight the monsters you were in range of. Even if this decreases rewards, it's nicer to just make the walk, and then deal with it when you're in some place warm, or not in a crowded area etc.
Not everyone lives in warm places, and some may not like to stand around in public just to play a mobile game.
Multiple characters, even if this is only a VIP (that backers get) feature.
Ability to reset stat points, and not only through paying money for it.