Hi.
I play col2 for about 2 years and i want to improve my knowladge.
I have problems with:
- what talents should i use for: great sage, won ton, abyss demon, renee ven, chiron, arcane caster?
- what items should i use for what heroes?
- how to conter wolvenfiend !?

Most of the time, you want to increase ur hero atk or dmg via talents.  However, it isnt that easy to get what you want.  For example, dmg or atk speed talent is good for abyss where atk is better for arcane caster.  Damage reduction talent works for all heroes.  It depends on ur play style or what kind of aid do u have

As for weapon, it depends on the game mode.  For gc, arena and coliseum, u want tyrant.  For bs, the axe is more useful.  

Hope this help.

For talents just use those talents which boost heroes attributes, i have not used talents much though.
For example, Abyss Demon needs stronger attack rate, because stronger it attacks stronger it heals, Weapon- Thunderblade
1) Tanks like Landslide, Berserker, Wolvenfiend need higher HP talents, Weapon - Dragon Heart
2) Wizards(Damage Dealers/low health) like Ambrosia,Pan Goli need higher attack/or attack rate talents, Weapon - Arcane Tome
3) Stunners(Locks enemy) like Won Ton and Great Sage you need Weapon like- Holy Hammer
4) Sharpshooters like chiron and Renee Ven, weapon like Thorned Bow
5) Witches like Arcane Caster and Enchantress, I usually would go for weapons like Tyrant Brand which increase their resistance to damage and increase damage.
Not used axe yet