Absolutely.
The army:
Paladins
Knights
Horsemen
Ghosts
Cursed Ghosts
- can do it with minimal losses. However, you'll be facing one really big problem all the time. Both ghosts must feed equally. Otherwise they'll simply outgrow their stacks and go out of control. I have confirmed it, that happens. The next thing you should be aware of is that if one of the ghosts isn't feeding enough, the stack will be killed by Ktahu's spits.
With any luck, this can be done without losses. But it must really be a stroke of luck, because come to think of it, there is no way that you can ensure that the ghosts will remain at their max leadership by the time you kill K'tahu.
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