Poison Spell Interrupting Spellcasting

Currently it seems that the initial application of the Poison spell will interrupt the target player, this interrupt will also persist on characters that are already poisoned. The initial tick does 0 damage to the player and will interrupt even if resisted. This essentially makes the poison spell a debuff with a DOT factor.

I have spent some time looking for evidence whether the initial cast of the poisoning spell interrupts, however the only evidence I could find was relating to the poison ticks interrupting spellcasting. I also have vague memories of monsters casting poison on my character during UO:R and finishing the spellcast before the first poison tick.

I have attached two RPV's of my character being interrupted by the poison spell while unpoisoned and being interrupted while poisoned.

Unpoisoned and Unpoisoned interrupt:
http://www.mediafire.com/download.php?vu9172l7o5d61mq
Poisoned:
http://www.mediafire.com/download.php?5j5o2vbx8qzwpyb

Poison is the deciding factor in a 5x mage duel. Interrupting is the most important part to stop the heal and cure, by harm,poison,lightning.

Debuff's also interrupt without doing any damage such as weaken or clumsy.

Absolutely right, although I didn't take part in too many duels during the OSI days I do remember from watching that if poison was precasted it was only used to reapply the poison when cured, never for an interrupt.
Spells like harm, lightning and magic arrow were used alongside the regular debuffs in order to interrupt spellcasting, I cannot say for certain whether this was because the initial cast of poison did not interrupt or because it was more mana/damage/speed effective to use the others. The reason I draw attention to this is because I have no personal recollections of the poison cast actually interrupting spellcasting, I have vivid memories of spellcasters hitting my char with poison mid cast and the spell would finish before the first tick of poison would hit.

It's entirely possible that my memory is off, but it just doesn't make sense that poisoning an already poisoned player would interrupt the spellcast.

Though I don't have any documentation in front of me, I do believe that this is correct. The initial application of the poison spell should not interrupt a player's spell casting process, only the actual damage-tick should cause interruption. If my referencing is correct, this should be a specific feature of the poison spell since it does 0 damage on targeting, thus yielding no interruption, but is not linked to other 0 damage offensive spells, such as debuffs (weaken, clumsy, etc)

I'll have to verify whether or not this correct. Thanks for the report.

Incorrect boss. The initial poison spell is supposed to interrupt upon application. That was always key in duels was trying to time a cure between the poison application and the explosion damage. I remember repeatedly being disrupted by the actual poison spell in duels.

If the poison spell didn't interrupt upon application that would mean that if you tried to reapply it on your opponent, and the resisted it, they would be able to get a Gheal up every time which was not the case. It disrupts because it is an aggro spell even though the initial application doesn't cause immediate damage. It's no different than how debuffs work.