I'm under the impression that duel mode is not particularly needed for the game. I feel that you could simply merge the reward system of duel mode with the ranking progression of 'ranked mode' Rewarding players with both currencies as well as leaderboard ranks. You'd tie up players from both player bases into one place, and everyone prospers
with that said...What's going to fit in the place of duel mode.
So coop and PVE is one of this game's strong suits, and I feel a mode which would remove all of the barriers and just give folks a challenge would be golden.
Basically what you'd do is:
1)Take the progression through levels that is in duel mode
2)Allow players to invite friends
3)Rework how AI get's it's handicap with higher levels.
Had an idea in another thread were you'd adjust different variables as you proceeded like..(copy + paste)
The AI wizard had these 3 values that increased with level:
a) Increase mana gained per turn
b) Increased value of spells in deck
c) Reinforcements on start of match
d?)Other possibilities could be simply tweaking up the various stats of a wizard such as there melee,defense,magic power,deck amount,boosting bonus, etc. This could possibly take the place of b), as you could incorporate more variety in their. Randomly allocating stats to wizards as you level up.
Perhaps with these 3 variables you could have something that scales up in a well paced way.
lvl 1 - AI on it's own (0a)(0b)(0c)
lvl 2 - AI with (1a)(.5b)(0c)
lvl 3 - AI with (2a)(1b)(0c)
lvl 4 - AI with (2a)(1b)(1c)
lvl 5 - AI with (3a)(1.5b)(1c)
lvl 6 - AI with (4a)(2b)(1c)
lvl 7 - AI with (4a)(2b)(2c)
lvl 8 - AI with (5a)(2.5b)(2c)
lvl16 - AI with (10a)(5b)(4c)
The variables themselves are not really specified....Just if you had a few variables to dial up as progression took place.
I feel like something that scaled up to 30 levels might be a good place...of course you could have it go forever for whoever is up for that challenge but pacing it for about 30 levels to achieve something. Just something that's freakin hard to get to lvl 20, really trying your patients going to 30, and from there just have a pissing contest to who can get beyond lvl 40..heh
Perhaps for the experienced players, you could have an unlockable level cap were you can just jump in at level 10 or something of the sort as suggested by noworries (irc) This way players who play enough can easily begin at their appropriate skill level and go for the higher number.