I'm the AI and I think you players have it easy.  I mean c'mon.  Once you get a stack of 3-4 champions together, what am I supposed to do to stop you, huh?  Look at the numbskulls I'm stuck with.  Ogres?  They're tough, but they aren't smart enough to stop attacking your tanky champs you hang out front like red meat and go around and pound your squishy casters into the ground like a tent peg.  Nowhere near smart enought to back off when critically injured and let their regeneration kick in.  And honestly, how many ogres would it take to actually kill those guys?  The more I throw at you the more powerful they get, so what's the point.  Drakes?  Sure, they're big and scary, but they are too slow to actually chase you down and kill you when you are weak.  You just run away and come back with more troops and all the fancy equipment you took from the stupid Trolls.  Come to think of it, I can't ever chase you down unless you are as dumb as you are cocky and come too close.  (If only I had units with 3 or 4 moves like some of your champions.  Then you would pay...)  Now if I was allowed to, I would run away from your blasted champions when they are too much for me to take all at once, regroup, and then gather together a real army and show you how we do it in the wildlands.  You want to put together an epic stack of doom, fine, so will I.  No more of these little scouting parties that keep to themselves.  You think 4 trolls is easy?  Try 10 or 15!  Oh, and while your champions are out looking for my lairs to destroy, my darklings and spiders are coming after your cities without mercy.  Nothing makes darklings happier than some nice militia stew with some civilian-slaw and spearmen-kababs.

Just a word of warning, Tinkerbell.  You are no longer safe on my turf. Be afraid.