OK, the exact mechanics of this skill escape me. I get the bonus HP. That's easy to understand. I also think I get that the sandstorm causes every enemy in the AoE to take 3/4/5% of the maximum HP as magic damage every second. What I don't get is how this is converted to attack damage. Does Nasus get a flat AD bonus equal to the total magic damage he deals each second with the storm (maxing at 240 per target), or does he get a percentage increase for every target in range? My friend was under the understanding that the storm actually increases the damage enemies TAKE by a percentage in a manner similar to Vlad's Hemoplague, but I don't see how that works. Could someone clear this up for me please? The skill description on the wiki is pretty vague.
EDIT: Also, does anyone know what the exact AoE range is? The visual effect is a bit hard to judge, especially in the cluster**** of a teamfight, and the wiki doesn't list it.