Explanation leads to contradiction.
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Savathûn didn't construct her Spire for Light and logic alone. There is more to this than meets the eye. That's the crux of it.
What is imbaru? Asking the question yields an ounce of tribute by itself; failing to answer it yields more. It's impossible to engage with the concept without falling into the web of cunning devised by the Witch Queen, even after her death.
It's elegant. And irritating.
We are familiar with the sword logic: the need to endure and force the universe to endure you. It's a contest. When there is nothing left standing but you, then you've won. Your prize is existence.
But imbaru is tribute from the failure to understand. When Savathûn ensnared us with her cunning, she fed her worm. Every false step or mistake in our attempts to unravel Savathûn's plans gave her exactly what she wanted. Whenever someone believed a lie or doubted a truth, she became that much more powerful.
We might think we know what we're doing here, but in many ways, I doubt we do. There will be ripples from Eris's actions. We can't predict what waves she'll make.