AST MP Issue?

[GideonHighmourn]

An ewer or even an enhanced ewer can help out a blackmage on DPS checks by allowing them to cast an extra Fire (w.e level) before switching to ice.

Only if they received Ewer before they started their rotation, and only if they knew they received Ewer prior to starting. You're assuming it was pulled while they were at full MP and were aware they actually received the buff; unless you're on VOIP and can communicate that, it's not really doing much for them. I think Ewer is best used on yourself or the other healer, since chances are you're both going to be casting fairly regularly; however, using it (or spear) on yourself defeats the purpose of bringing AST for group utility, as has been discussed before.