When I was in my teens we had a house fire that lit up all the 80's polystyrene hallway ceiling tiles and near completely filled the stairway with flames. With familiarity with the steps, I ran down through the flame and, despite having my hair singed and eyelashes shortened, I remained fine, physically.
If I'd run through a cloud of daggers or if any of the blobs of melting polystyrene fell on me, that might have been different but Flaming Sphere is reasonable.
When our group used Flaming Sphere to clear out rooms and corridors of spiders, we kept moving the sphere in front and kept following behind.
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I like the idea of occupying spaces within 10ft of a Flaming Sphere but am unsure how this would work with a moving sphere. Readied action just lets you have one thing readied but, ideally, when, on the caster's turn, the sphere is moved, other characters might want to follow the sphere
and still be ready to attack an opponent coming into range. Perhaps the way to do it would be to set the ready trigger of an opposing creature entering the sphere as a trigger to move, block and attack them.