It seems it can "Cast" and Proc at the same time.
Gave a mob a 100% chance to proc Death Touch and gave her 2 spells Combustion and Ice Comet. (5 sec cooldown on Combustion and 20 sec cooldown on Comet)
Every combat round she would DT ... and use 1 spell if it was ready going in priority.
-1 for mana cost -- seems to use the mana cost from the database
-1 for recast -- seems to use the recast from the database! So I did this...
SELECT * FROM spells_new WHERE recast_time = 0 AND goodeffect = 0 AND effectid1 = 0;
Grabbed a random DMG spell that i created that was a 1000dmg Nuke with NO cast time and NO Recast time...
I set -1 as the recast inside the npcspellentries (so it grabs the recast time from the spells table) ... now the NPC has a Gatling Gun spell that she spam casts like shes Al Capone mowing down some mobsters.
Loping Plains Acid Rain -- has 0 cast 0 Delay ... (unless its a proc only)
Frozen Poison III -- has 0 cast 0 Delay ... (unless its a proc only)
But if you have this spell on a Cast List ... then you must add a recast time otherwise it will be 0 sec recast with 0 cast time... making them Bringer's of Death... doing 100k AoEs every attack round... going pew pew pew!