Before I go into all the options that use either Kossars, Kossars (Spears), or Ice Guard, you should know how to set them up. If you just line them up in a long line, the enemy is going to charge into them, prevent them from shooting, or end up mulching them in melee and you will lose.
Instead look at the image above and follow this advice. Let’s says you have 14 Kossars (Spears) or Ice Guard, doesn’t matter because it works the same for both.
You take 7 of them, and create a line. Then select the 2nd unit from the right, the middle unit, and the 2nd unit from the left, and then on your keyboard, look at the arrow keys below Delete, End, Page Down, with those units selected press the Down Arrow Key 2-3 times.
Then line up the other 7 behind those 3 creating a third line. You could leave that third line as is, it may be fine, or you can again select the 2nd unit from right, the middle, and 2nd from left of the third line, press the down key 2-3 times, and now you have a 4th line. If you have another 2-4 units, you can probably figure out where to put them if you follow the pattern of the formation.
This formation seems to confuse the AI who hesitate to charge, and if they do, they get stuck on the outer units will those behind are able to continue firing. This also allows unit to rotate as needed to target different threats, especially if you keep the unit as square as you can instead of being in a thin line.
Doing this I was able to beat Khorne and Slaanesh armies that I probably would have lost handily to if I had just lined my forces up in a line like a newbie.
KATARIN OPTION 1
You get your 3 Frost Maidens (1 with Ice Magic and the other 2 with Tempest Magic) and 1 Patriarch asap and embed them with Katarin. Max Scouting with just 1 of the Frost Maidens, max Replenish Troops and Salyak’s Lullaby (and get Healer at Rank 21) with the Patriarch. Fill the rest of Katarin’s army with Kossars (Spears). With Katarin and your Ice Magic Frost Maiden use Ice Sheets to slow down the enemy while your Tempest Frost Maidens cast Upgraded Gust of True Flight on as many Kossars (Spears) as they can, then have Katarin & Maidens use Guardian Call to summon 4 snow leopards to tank the enemy, then when the leopards die use your Lord and Heroes all on War Bears to tank the enemy, all while your Kossars rain death on the enemy. The Patriarch heals Lord & Heroes with Salyak’s Lullaby at the end of the battle.
When you are able to, transfer all the Kossars (Spears) to another lord and replace them with Ice Guard (I’d go all Glaives for the Armor Piercing and Anti-Large but if money is terribly tight or you want some of them to be anti-infantry you could go half Glaives and the rest regular Ice Guard)
Use the exact same strategy that worked with Kossars (Spears) with the Ice Guard.
This army is basically a light Doomstack so you should have no problem beating the campaign once you have your Ice Guard Doomstack-lite.
Same as 1 but instead of Frost Maidens you put 3+ Patriarchs in Katarin’s army. Katarin and the Patriarchs (ideally on War Bears) will tank the enemy while your archers rain death. The Patriarchs can heal everyone with Salyak’s Lullaby. Upgrade to Ice Guard when able same as before. The benefit of this is that maxed combat skills Patriarchs (particularly equipped with magic items) and very tanky and deadly.
Same as Option 2 but if only one Replenish Troops will benefit the army, then have Katarin and 1 Patriarch who has max Replenish Troops and Salyak’s Lullaby, and then have the other “tank” units be Snow Leopards or War Bear Riders or War Sleds (Light or Heavy) and finally Elemental Bears. If Elemental Bears, use the Patriarch’s Salyak’s Lullaby to heal all the single-entities at the end of the battle.
Replace Kossars with Ice Guard when able
Option 3.5 is have Katarin and 1 Patriarch with those same skills, and have the rest just be Kossars (Spears) then Ice Guard when able, make up for lack of heroes with increased firepower.
Once you get him, Boris Ursus could go all War Bear Riders with 1 Patriarch for healing and replenishment, since Boris gives -50% upkeep for War Bear Riders.
Kostaltyn does not buff any specific unit, but he does reduce recruitment costs to 0, so use him to recruit everything if you can. I’m not even sure how he does it. Firebrand reduces recruitment cost by -50%. The Burning Brazier by -10%. Leader of Renown by -15%. He got the Musterer trait which gives -5%. He has a Militiaman follower who gives -5% for infantry. That’s -85%, but under Campaign Effects it says -80%, so not -100%, and he is not in a province with the Relief Columns commandment active, yet he can recruit even Elemental Bears from the Global Recruitment Pool for 0 gold. Crazy.
Oh, but if you start your campaign as Kostaltyn, then Patriarchs get 20% Ward Save. Which means you give Kostaltyn 19 Patriarchs on War Bears with maxed Combat skills and Salyak’s Lullaby to heal and you have a proper Doomstack.
Ice Witches can copy Katarin’s army composition both with Kossars (Spears) and Ice Guard, but Ice Guard will be their normal price and Ice Witches aren’t as tanky as Katarin is. Or…
LIGHT WAR SLEDS
^ you can read the comments from that post to verify what I’m saying below.
Light War Sleds are ridiculously good. If Ogres terrify you, bring Light War Sleds. LWS can kite while shooting with Armor Piercing missiles (and they have a ton of ammo), they can snipe lords and single monsters like Stonehorns, and then once all the single entities and anti-large units are dead and if they are out of ammo, they can charge into infantry like chariots and as long as you keep them moving and cycle charging (which is a lot easier with sleds than cavalry) they will eventually slaughter all the infantry.
And if you mess up an a few sled units die, LWS are just 1 turn to replace, even from Global Recruitment if you have the Citadel of Praag unique building built. I haven’t tested this out myself yet, but u/Clawsonflakes says that Heavy War Sleds are even better because “they’re invulnerable” and don’t die.
Now, Light War Sleds are faster than Heavy War Sleds, which may make them better at running away from enemy anti-large, but if Heavy War Sleds are really that tough and have even more mass for charging through infantry, they may be a true doomstack. I would possibly consider a stack of Light War Sleds to be a Doomstack, or at least a Doomstack-Lite.
Also, during training, Ice Witches and Frost Maidens may get the prompt to choose between 2 traits, one trait that gives -30% upkeep for War Sleds, and one that gives -30% upkeep for Little Grom units. I always choose War Sleds. If you have an Ice Witch with that -30% War Sled trait, plus the -17% upkeep from Quartermaster and Renowned & Feared, combined with just 1 Frost Maiden with the -30% War Sled trait, that is -77% upkeep for War Sleds. Add 1 more Frost Maiden with -30% War Sled Upkeep, and you have -107% upkeep for War Sleds.
And of course, Elemental Bears are probably Kislev’s version of Carnosaurs or War Hydras or Dragons, etc, that is to say Doomstack material. Basically make a full stack of Elemental Bears with 1-3 Patriarchs on War Bears with Salyak’s Lullaby to heal them back to full health at the end of the battle, and you have a true Doomstack.