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Oh wait, NT were you talking specifically about the curse-poison combo?
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Thats true NT, but the objective of the poison army is to wipe out regular troops in the early-mid stages of the game. After that its just a powerful tool in the box of strategies available to you later on. But you shouldnt think that a Hydra-poison army is particular vulernable to SCs. First of all, by the same token you can deploy all your own undead thugs/SCs with that army without any fear which basically balances things out. And even that aside, Hydra's are surprisingly tough against SCs. They have a ton of attacks to reduce defense and thier hits are pretty hard as well. Not to mention that each head maxes out at 6hp damage so there is only so much damage an SC can do per turn.
I'd also considered writing an anti-SC segment in the late game part of the guide as well. But it was already so long I didnt want to make it any bigger