What is the best way to add poison to a creature's attack?

I'm using Malo et al's custom spider, and I can get it to cast a touch spell on the player to simulate poison when it hits, but it plays the destruction magic shader when it happens and ignores any poison resistance the player might have. I tried setting the spell to poison but it does nothing at all with this setting. I also tried adding a poison potion to the player and equipping it but it just adds poison to the player's weapon. I can't equip the spider with a weapon which is the only way I can add poison to it's attack using normal methods. Any suggestions? It has to act like a poison with normal resistances and either play the poison shader or no shader.

Why not a scripted effect?

Assuming you are using OBSE you can check the poison resistance of the target, apply this to the damage, inflict the health damage on target and it will not show any effects as long as you set it that way in the spell (effects none).

You could attach a script to the touch spell and have the script play and stop the poison shader. Use PMS effectPoison to start playing the shader and SMS effectPoison to stop it.

Thanks to both for the replies. I pretty much figured I'd have to script it, but I didn't want to if there was an easier way of doing it that I'd somehow missed.

I pretty much have it working now (just needs some testing and tweaking), though I'm not getting consistent results with the poison shader. I'll have to look into that. I've designed it to be generic so that I can just put in new values for duration and magnitude and the script will handle the rest. Also handles resistance to poison and weakness to poison effects.

Thanks again for the help.