@fishhead1982Would Leomunds Tiny Hut be able to be cast, and then stay on, an Ancient Dragon? Asking for a friend. You could cast the spell while on the dragon, but I think the hut would slide off.
— Jeremy Crawford (@JeremyECrawford) April 17, 2017
@fishhead1982Would Leomunds Tiny Hut be able to be cast, and then stay on, an Ancient Dragon? Asking for a friend. You could cast the spell while on the dragon, but I think the hut would slide off.
— Jeremy Crawford (@JeremyECrawford) April 17, 2017
According to the RAW the Tiny Hut is “A 10-foot-radius immobile dome”. The hut would stay where it was cast. The dragon could simply fly or walk away and the hut would remain suspended in space.
says “immobile” so it either anchors the dragon or stays on its back (or the rule needs to be rewritten in errata).
or like Erik says above, the Dragon simply moves out from under it and the dome/hemisphere stays put.
And since a hemisphere has a plane bisecting it, thus giving it a shape and therefore a floor (since the dome itself must appear above you, and not like a bowl below you), then you could still stand in it.
I just realized something critical in this example: You don’t cast Tiny Hut on things but rather around yourself, so it’s simply the location you were standing in. This means if casting “on a dragon” (you’d be standing where the dragon is on the gameboard) the spell would immediately fail from including a creature which is larger than Medium. And it takes a minute to cast, so unless the Dragon is just trying to help you pitch a tent some distance off the ground, you’re not even going to get the opportunity to cast it (assuming someone is saying, “I’m standing on their back, above the dragon, so the dragon is not inside the hemisphere”)