Creo que cada hit de arcane missiles tiene una chance de activar el proc de clearcasting, aclaro por si ven el proc seguido.
Arcane Concentration - Spell - World of Warcraft
Additionally, Clearcast can procc of the initial cast of Arcane Missiles aswell as of any of the 5 missiles. This I know for a fact, since it has happened many times to me.
That would mean Clearcast could procc of any hit from a Blizzard aswell, but I've never seen that happen. Not saying it hasn't, only that I've never noticed it.
On the other hand the mecanics for Blizzard and Arcane Missiles may differ, since Blizzard is AoE and AM is one-target-direct-dmg.
Could also add that it seems as if Clearcast has a higher chance to proc of a crit than a normal hit, but if that's acctually true I suppose it's some bug.
Aswell as if a Clearcast proccs of the initial cast of arcane missiles, it seems the whole missile (where I recived the Clearcast) and the missile where I accutally use the clearcast both benefits from the extra crit from arcane potency.
Jaja, tenes razon con lo de missile barrage, tmb hace procear arcane potency.