Hah, I've got my own TWH3 ownage story. (Also an ambush.)
I'm playing a Norsca campaign. I'd taken over all of Norsca pretty early on and was working on trashing Kislev and working into the Empire....
When the Daemons of Chaos faction declared war on me, due to anti-player bias. So they landed a couple armies on the north coast of Norsca and I had to send a couple armies up there to deal with them.
One army was a Skin Wolf doomstack. Nothing but Skinwolves, Skin Wolf Hero, normal lord and shaman on horseback, and a couple Marauder Horsemasters. So a very mobile army, which made all the difference.
So I ambush a Daemons of Chaos army and it's at least half regiments of renown, chaos warriors of Slaanesh, pink and blue horrors and, worst of all, Rot Knights. Oh, and Aekold Helbrass as a hero.
Since I had an almost entirely melee force I rushed in. My lord and SW Hero struggled against the Daemon of Slaanesh lord right from the outset. The squishier units like pink and blue horrors and Chaos furies wipe pretty quickly. But the Chaos Warriors, Regiment of Renown Chaos Giant and the Rot Knights absolutely fuck up my skin wolves. Particularly the Rot Knights who knock down infantry health by 50% in one good charge. My skin wolves start retreating from the fight almost immediately. Things are not looking good.
But here's the thing about skin wolves: they're fucking fast. Faster than almost any infantry and almost as fast as medium cavalry. And they regen. So they break and run but quickly outdistance chaos warriors immediately and return to the fight with more health than they fled it with.
My lord and hero eventually down the enemy lord, and turn to face Aekold Helbrass, who is tanking both of their damage and multiple skin wolf units despite only being rank 9. If he'd been higher rank and had his AoE heal, I'm pretty sure I would have lost the fight.
Things are looking pretty grim though. All the toughest units are mostly full health and have barrier to boot, my skin wolves are uniformly at 30% health or less, the Rot Knights are unfightable in melee, the Chaos Giant is flattening units left and right in melee, and the Chaos Warriors are so tough that there's no chance my skin wolves can make any real progress against them.
So what do? Well, I channeled my inner Legend of Total War. I realized that, of the units left, nothing is faster than the slowest unit in my army. So I run my forces around the map, separating the AI and pick off the Rot Knights with my Marauder Horsemasters. The whole time I'm kiting the remainder of the army around, almost all my units are regenerating. I finish off a couple more almost dead units like Forsaken with my Marauder Horsemasters, and eventually position my army in one place while the remainder of the enemy forces are scattered about. I use the now ammo-depleted Horsemasters to kite away the Severed Claw (regiment of renown Aspiring Champions, probably the nastiest RoR unit in the Chaos roster) while the rest of my army dog piles Aekold Helbrass and down him in just a few seconds. That gave me the army loses and I won. With my entire army more or less being at full health thanks to regen. If I'm honest, it was really the regen that pushed the balance of power to the point I didn't need to wipe out all their toughest units to get the army loses.
Felt good. Even though it's cheesing the AI with fast units, I could have easily lost that battle if I'd just yolo'd my units in there.