Hi.
I've played heroes charge for a while but now I'm stuck on the first stage on elite campaign chapter X (10) so I would appreciate some help on which heroes I should max and use.
I'm level 69 so I'll bold the names of the heroes that's maxed.

Front:
Bear Warrior ***
Arcane Sapper ****
War Chief **

Admiral ***
Death Knight ***
Cleric ***
Shallows Keeper **
Depths Voice **
Psychopath *
Savage One **
Mountain **


Central:
Succubus ***
Lightning Master **
Emberstar ***
Frost Mage **
Ice Mage **
Shadow Shaman **
Old Curse **
Machinist **
Ferryman **
Lunar Guard ***
Necromancer **
Silencer **
Vengeance Spirit ***
Imperial Executioner **


Back:
Wind Master ****
Commando ****

Leaves Shadow ***
Chaplain ***
Sniper **
Mystic **
Pilot **
Rifleman **
Professional Killer ***

My current setup's are:
1- Bear Warrior, War Chief, Wind Master, Commando and Leaves Shadow
2- Death Knight, Arcane Sapper, Wind Master, Commando and Leaves Shadow
3- Bear Warrior/Death Knight, Arcane Sapper, War Chief/Bear Warrior, Commando, Wind Master

Any suggestions on which heroes I should max and use are welcome because at the moment I don't know which of my heroes I that's best to upgrade and it's a little to expensive to max a hero that won't help me.