Hall Servants had the first turn each round. Went through several rounds and I had cast a 'Convert Ice to Fire' at some point on Servant 1.
On the current round, Servant 2 cast a 'Fire Defense (Shield)' on Servant 1. So Servant 1 had both the 'Convert' and the 'Fire Defense' on him. On my turn during the SAME round, I cast an Ice spell on Servant 1.
The Ice spell was converted to Fire for the Boost. However, the Fire Defense did not work. This has happened to me twice now that I've noticed.
This benefited me but I don't believe it was meant to work that way.
If the Fire Defense was already there before I cast the Convert, it seemed to kick in fine.
Re: Possible timing bug with fire defense and convert
The order of operations for shields, traps, and prisms is that it checks the most recently cast first to see if it applies, then the next most recently cast, and so forth, all the way back to the first one placed.
The game started by checking the fire shield and saw that it didn't apply. Then it checked the prism, which converted the ice damage to fire. It did not check the fire shield again, as that had already been checked and found to not apply.
If the mob had cast the fire shield before you cast the prism, then it would have applied the prism first, then checked the shield, and found that the shield should apply.
Consider what would have happened if it had been a snow shield instead. In this case, the snow shield would have applied if cast after the prism, but not if cast before the prism. That is, it would be the opposite of the behavior for a fire shield.
You might argue that this is odd and whether the shield applies should not depend on the order of operations. If it did not, then should a fire shield count? How about a snow shield? If someone uses a thermic shield (both fire and ice shields), should both shields be applied? Neither? No matter how the game resolves the attack, it's going to seem odd.
The order of operations is consistent and easy to understand, at least. Whether or not it's how it was intended to work, I think it works just fine as it is.