Nuntar wrote:
Your start is incorrect.

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×When the mimic reaches (17,4), you need to move it 6 tiles west and 6 south. The shape of Beethro's box gives you 2 west and 4 south moves; each time you push against the snake it will shorten, so you can get another 4 before it dies. That leaves you two short, so you need to find another two west or south moves from somewhere...

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×...which means you need to move Beethro east or north without the mimic moving...

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×...which can only happen at one specific place.

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×The trapdoor where the mimic starts.