Hrmm... Fireballs are quite slow compared to a bullet.
Plus. This.
RT(Reaction time) is fastest when there is only one possible response (simple reaction time) and becomes slower as additional response options are added (choice reaction time). According to Hick's law, choice reaction time increases in proportion to the logarithm of the number of response alternatives.
Simple reaction time is the time required for an observer to respond to the presence of a stimulus. For example, a subject might be asked to press a button as soon as a light or sound appears. Mean RT for young adults is approximately 190 milliseconds to a detect visual stimulus, and approximately 160 milliseconds to detect an auditory stimulus.
Researchers have reported modest, but statistically significant correlations between measures of reaction time and intelligence. Although there are numerous exceptions, there is an overall tendency for individuals with higher IQ to be slightly faster on reaction time tests.
So yeah, Good luck on dodging a bullet. =)