You've done the hard part, just walk past the last two slayers. Remember, when Beethro is close by, a slayer has different movement rules. He doesn't keep following his wisp. Instead, he steps or turns or stops in order to maintain his defense or attack, if absolutely safe. In this room, it's best to stop wasting time with trial and error and start thinking about slayer movement patterns. Also, it's easier to walk past each one separately, without letting them bunch up.
Some different ways to walk past slayers:
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×1. Here, as Beethro moves west, the slayer goes east to get behind Beethro.
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S-
-B
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2. Here, as Beethro moves west, the slayer stops altogether in defense. This also works for going past several slayers at once.
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S
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B
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3. In a situation like this, Beethro should step south, so that the slayer will step north to get behind Beethro. Then you can maneuver into one of the two cases above.
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/ B S
S / B
/
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4. Finally, in a situation like this, Beethro should turn his sword southwest so that the slayer will also step north to get behind Beethro. He can turn his sword back to west and continue from there.
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S-
S-
-B B
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And of course, all of these situations could be reflected vertically.