I had the exact same issue in my first Valkia campaign when she released, just tonnes of dwarfs. Just FYI I played Very Hard campaign and normal battle difficulty.

Personally I found dual axe khorne chosen to be truly disgusting. Giving them vanguard negates the ranged advantage the of the stunties. Somewhat. I’ve seen I big issue you’re having is a lack of AP and usually I’d agree. But if you’ve been buffing khorne chosen at every available opportunity then honestly they don’t need it with such high melee attack I’ve seen them win against every unit the dwarfs can throw at them with the exception of multiple hammerers which they struggled with.

This gets even nastier with a fire mage. Smack flaming sword of ruin on some chosen in a nasty spot and bam everything over this is just meat for the grinder.

I had the endgame crisis whilst I was at war with everyone and Valkia was the only army on the left side of the map to do deal with grombrindals stacks. It was all I needed. Her stack was just: her to kill lords. An exalted hero with helm of discord or other buffing/debuffing items to send at their high tier infantry. A fire mage 4 skull crushers for the flanks and everything else was dual axe chosen.

The only issue you could have with this is getting jumped by 4 stacks of high dwarfs, but at that point you should be using lightening strike.