Problem:
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Vanish makes you completely invisible for a full turn.
You can do a full lair by simply using vanish followed by recover (will be long, but if you have the willpower you can use dash or move for a turn and use recover only on the next one).
You can kill everybody with enough time.
Suggestion:
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Vanish should only restore your +25% stealth. Not make you invisible. That means that the yellow dots would only show locations that satisfy "not losing it immediately".