So on my first shard I tried out my first Arena fight - with my Level 7 Ranger. Was faced against Level 13 Warrior.

The warrior just stood still and kept casting spells (first turn - Stone shower on my entire party... )

I was able to trade his army for mine just barely with only my Ranger hero still standing to face the Warrior who finally ran out of spells to cast. That was the first time I looked at his stats - he could have probably taken on my entire party by himself if he just charged into the fight.

He had 9 points of Magic resistance, even higher Ranged and Melee defense ratings.

I currently have Ranger and Wizard heroes, Wizard is my main - but against a resistance that high, most of the Wizard's debuff spells wouldn't even stick and even with the level 4 Inciniration damage spells would hardly trouble him.

So my question is, is it even feasible to win any of those Champion fights unless you are bringing a max level Hero into them? (Other than religiously mining medals from each combat to build up a army of super-soldiers?)

Thing with arena is complete randomness of the gear, spells, units, and level distribution.
It means that very low level character can cast something ridiculous (my personal experience - at level 4 I faced wizard with summon phoenix) or be geared into legendary items.
To be able feasibly win these fights you need to bring similarly ridiculous hero. Low level wizard with M4 Summon spell, Low level commander with Hydra, warrior in purple items...

As for 9 resist on warrior - if your wizard has resist penetration (above 4), it can put vulnerability on warrior and it would work. Second Vulnerability would decrease resist to zero.

I tried a few times, but i have never won an arena fight.... on any difficulty level! did not even come close! as far as i can tell it is totally stupid and pointless, I just ignore that wasted code.

Naw, the Arena is great.

Sometimes you get really easy fights and sometimes you get really hard ones.

If you win enough matches you become the arena champion and get some nice prizes.

Ahhh i get it now, so i just 'happened' to get all 'hard' ones..... of course!

I am not blaming you, i am pissed because this is exactly the type of little annoying thing 'game luck' loves to do to me when things are left up to chance. Now that i know, you watch, all of a sudden i will start getting easier ones! lol

Ha! I understand.

Honestly though, if you try your luck in the Arena at Champion difficulty, you'll sometimes get fights that will blow your mind, as in, "How the hell am I supposed to win against THAT!?"

I still think it's fun though.

It's not like you HAVE to go inside. So it's better to have it in the game as an additional diversion. Plus you can always turn back time.
Best use I found is for secondary low level heroes who have the super gear.