Stacking red is pointless imo. Just stack your best non reds vs him.
You aren’t trying to kill Kashrek quickly, Kashrek has no offense and isn’t punishing at all. Kashrek is the least threatening hero on the opponents team. Kill him last. Or whenever convenient.
Scarecrow has it right.
Bring your best heroes (preferably non red). Use Kashrek as a sponge and send as many tiles at him as you can. Charge up 3 of your heroes and use them to take out the biggest threat on the opponent’s team (hint, not Kashrek). Rinse and repeat.
As scarecrow says he’s actually a pretty bad tank once you realize he’s a safe place to charge up your heroes. The way he punishes you is only if you stack reds. If you don’t stack any reds he has zero punish potential.
There is no such thing as bad board fighting Kasshrek. The best team when you fight him is rainbow one or at least 2-1-1-1. Especially at rush attacks. Playing smart only on the middle, you charge only him and only your specials, that’s all. I hope to encounter Kasshrek tank the next days; no such luck for me so far. And I will record it, for everyone still don’t know how to fight…
The enemy display wasn’t good at all Li Xiu in the wing buys me enough time. My main concerns were the Wukong and Li Xiu specials, so I focused on keep Grimm and Sabina alive so they could charge and fire when needed. I dropped tiles over Kashh and dispelled Wu as soon as he went off. Killed Li thanks to Grimm and Balta (Danza gave me swords twice)
Cyprian was the last standing.
If I had this team I would have gone Wu, Kashh, Cyp, Lixiu, Kellile.
But most important: Before getting Sabina I would be forced to stack 3* reds to kill Kashh fast enough before the enemy defeated me by slashing also Having no time to hold specials.
Those passive tanks need fast hitters to avoid the attacker build a defense. Learnt a lot from this fight.