Thank you for the answer, Lydia!
However, this is absurd. How could melee units hit Sea Deity from the first row tiles if they were not in direct contact with the boss? I understand that the vortex battle design has a problem, rather than the whole player community suffering collective hallucination here. "In fact, the heroes in the front row were far away from Sea Deity", how in the world are we supposed to know that if empirically the contrary appears to be true in EVERY other instances??
We simply ask for a fix, there are various options: update Sea Deity battle's code since this issue involving the "in contact" mechanics will appear again in the future, or modify Rose's ulti to something useful somehow (ex: reduce the healing amount and make it effective for the whole map), or refund scrolls spent on this champion based on trusting the description to be true...
I love this game and I gladly support it by spending some real money on it, but this flawed mechanic and the team's response are very disappointing.
Mistakes are okay but defending them in the face of contradicting evidence is not... Please listen to your community!