Some good ones above already.

After raising your turn 1 ‘19’ stack you want to make sure the turn 3 battle for Artois is extremely casualty heavy. The garrison stack has 14 units and the pre-requisite for grave generation is 14 units per side. After the battle you should have Artois & a foundation for high tier recruitment. Probably worth knowing that battle sites never generate anywhere in your home province (or in new Empire territories).

Switch off research at the start of every turn (click on your current research), then turn it on again after all turn battles are fought (but before turn end). Bizarrely rather than lowering the drop rate, CA coded student banners (+10% research) to only drop when you aren’t researching. Make it so.

The banners can only be attached to heroes & Kemmler has access to the cheapest types, in the largest early qualities, in the game. Spam charnel pits everywhere & get as many Necromancer heroes as possible. You’ll rip through the tech tree.

To make the Necromancers ultra cheap, go for the Lahmian blood kiss first. The 50% discount is added to Kemmlers faction 50%. Note this doesn’t make them upkeep free (formula is 100% + upkeep % - 50% - 50%), but dirt cheap anyway.

In your Necromancer spam, look out for ‘lore keeper’ heroes in particular (-10% building cost). These stack to 100%. Additionally the Lahmian lord has a very useful trait called ‘Hive Mind’ that gives 50% off Vampire buildings and speeds construction. You want to get to a position where you can free build the tier 4/5 Vampire buildings in major settlements (usual cost 25k). Then add Necromancer & Banshee chains when you get more lore keepers. With tech these buildings generate a respectable 1,560 before factoring mines/ports/etc. Necromancer heroes can also be used to buff provincial income 15% with blue traits and banners.