0xAARRGGBB

Actually it's not really ARGB. The first half byte seems to specify the flash.
The second half specifies the speed of the flash. RR seems to be some kind
of "steps" that the transition takes. So setting that to 0x01-FF slows the flash down.
GG is the second color used for the flash, with BB being the main color,
both taken from the Mabinogi color table (color.xml).

AA: 40 = pulsate slow black to rgb
    41 = pulsate fast black to rgb
    42 = pulsate faster black to rgb
    43 = pulsate even faster black to rgb
    44 = pulsate "fastest" black to rgb
    45-49 = ... ridiculous fast
    50-59 = pulsate slow rgb to black
    60-69 = pulsate even from rgb to black
    70-79 = flickering rgb to black
    80-89 = flickering rgb to black (more "flickery")
    90-99 = flickering even rgb to black

    00  = RGB
    10  = First Color
    20  = Second Color
    30  = First Color?
    40+ = Flashies