I thought the Telvanni got overwhelmed?
And everyone knows Levitation is dangerous in higher climbs. Numerous Vvardenfellians have been caught in Red Mountain's mighty updraft, ripped through the atmosphere and landing in Akavir. Look at the Nerevarine--abused Stop-the-Moon-Shrine a bit too much
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edit,
Laziness, then. Because Morrowins'a dungeons did great things with levitation.
you know, I don't believe my old post the more i think about it. Mix of something-I-read and mindless-sheepism (i love grass).
TES3, I remember lots of clever things needing levitation. Quests included, like for the Fighters. Bandits were hidden. Run into their vampire associate.
Oh well. Laziness is a punk.