Trainer updated with part of the work on marks done (ctrl+F5)
http://www.elementsthegame.com/trainer.html
Marks will be upgradable several times when you have the required reputation with an element (Mark I to Mark X).
Each upgrade at the moment gives 5 extra HP's (to be balanced).
Upgraded marks can not be used in pvp.
It would be much better if the reputation is spent as a currency to unlock otherwise inaccessible rewards (random shard/new super-rares, along with the HP upgrades). That way the use of the reputation is more diverse, and the players
feel like they have control over the elemental they manifest into in the game, much like a real RPG, where you grow you character to the path you wish to. Small perks like attack bonus/hp bonus (like +1 for the atk or hp for cards of that element if nonzero) much like HD Xyth's campaign mode might work too. If you know about Tyrant, you know the reasons that the raid revamp worked because raid reputation can be spent and grinding got greatly improved. Elements is different from other CCGs, but it's always good to learn from the good things about others.
As for the balancing issue, I would recommend that you make small perks for different stats (10% chance to generate 1 extra quanta/+20HP/+1 atk/hp for nonzero creatres/15% to regain 1 qaunta when playing cards of that element) etc etc. Buffing 1 stat (health) to 150% sounds ridiculous and game-breaking, although the pvp enthusiasts would probably have already thought of pvp1 and 2 banning extra perks and adding pvp3 that allows them, which is also a quick and cost-effective solution.
To sidetrack even more, you see, bans make elements fun. Why not, instead of empowering the elemental, constrain him at battles for a gamble for bigger/rarer rewards?
Suggestions are called 2
because... well...