This may be a dumb question. Im not online at the moment, but if I remember correctly, the flare ability states that it uses remaining mana. So why cant you get down to 1 mp and use flare still? I tried the other day and I think I had 256 mana, and flare was greyed out and couldnt use it. What am I missing.

Also, just to clarify because I got lost in a sea of arguing, for single target rotations: Should I use flare every time? Or just when I have swift cast, flare, and raging strikes? What about if I only have Swiftcast up, would it be worth to use since it would be instant? Or would there be a dps loss of some sort, since flare without convert would require transpose and the slow mana ticking from UI 1.