[Gef]

Casting a spell takes your whole turn. You then roll for its success at the beginning of your next turn. This is not your action for turn 2, just the resolution of your action from turn 1. The reason for the delayed resolution is that somebody could attack and spoil your concentration. You may then proceed with your action for turn 2, which could be attacking with the flame jet you cast on turn 1 if it was successful, or it could be aiming a fireball.