Nasos
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If you're looking for a solution for 2 walls, there are quite a few ways to deal with 3 walls and one fake wall. I found at least 8. There are also a couple of options where, after the second wall, a stack of 20 Imps remained, which could be finished off with a stack of fakes without losses with normal RNG, but this is at the expense of the second criterion of the task.
It's a bit unclear.