I think Haynar's been playing around with the aoe spell code and some stuff intended for the rain spells crept over to the column spells.
http://www.project1999.org/forums/sh...t=26741&page=2
According to this archive link,
http://web.archive.org/web/200108210...as/aerain.html you can't get a killshot from a rain spell. To be honest it seems a little suspect to me. I don't ever remember the part about 100% resistance from rains at low hp, but my highest level wizard was only 15 on live. Maybe this code is still intact on the EQMac server. In any case, it shouldn't be applied to columns.