Hi, the T2 mage set can proc:
Netherwind Focus: “10% chance after casting Arcane Missiles, Fireball, or Frostbolt that your next spell with a casting time under 10 seconds cast instantly.”
Does each tick of the Missiles have the 10% chance? I watched some videos and it seems like they can, but the videos weren’t from the official servers I’m afraid.
I’d like to get a 100% correct answer. If you have the set for example on ERA, could you please test it with the Arcane Missiles?
Your best bet is asking in Classic Mage Discord. Someone will either answer or smugly point you toward a sticky. I seem to recall that channeled spells like Blizzard and AM only ever proc effects like AC or tier set bonuses upon initial cast. IIRC the proc happens before even the initial damage instance, so one can “fish” for procs by just repeatedly starting r1 AM or Blizz and going into gcd.