The spell description also states that the sphere causes damage by its flame, and that it stays at rest and burns if not actively directed. I take that to mean that it keeps doing burning damage.
Face it, the spell isn't written 100% unambiguously. You and I obviously interpret the intent differently. It would have to be in several pages of incomprehensible legalise otherwise. And then there still would have to be a Supreme Court or Rules Adjudication to clarify the authors intent.
Face it, the spell isn't written 100% unambiguously. You and I obviously interpret the intent differently. It would have to be in several pages of incomprehensible legalise otherwise. And then there still would have to be a Supreme Court or Rules Adjudication to clarify the authors intent.