Regarding the Turtle of Protection's Shelter, if the barrier can be of any size at the user's will, can one instance of this spell exist in several manipulable carapaces in similar fashion to, say, "Frieren: At Journey's End": multiple floating hexagons to deflect projectiles at the right angle? Or would that require multiple evocations? Additionally, how complex of a shape can the Shelter be? I reckon it's limited to simple geometric shapes like spheres, cubes, flat-sided polygons and the like.
I'd say there would have to be multiple activations of the powers to get your multiple floating hexagon idea (I've never seen Frieren: At Journey's End so I'm just going off of your description), but it is definitely possible. Or maybe a really skilled Turtle would be able to summon one Shellter and then split the panels apart and have them float off to different places?
As for the shape I'd say it has to always be in the vaguely-sphere-geometric-shapes that we see in canon. Not all sides have to be fully enclosing something, but there will always be a slight curve with how they link up. Dome and spheres beings the most common versions of Shellter.
