for freezing enemies, i'd recommend the rain spell to give enemies the "wet" status; this makes them take more damage from water and air spells, and a wet enemy who has had their magic armor depleted can be frozen (freezing an enemy requires applying either the "wet" or "chilled" status first, then using an ice spell like global cooling or winter blast). stunning an enemy, similar to freezing, requires applying either "wet" or "shocked" status to an enemy without magic armor, then using a lightning spell like electric discharge or dazing bolt; the easiest way this is done is using the rain spell before using damage spells. as Kalrakh mentioned, hard CC like freeze and stun can only be applied when the enemy has lost all their magic armor, just like knockdown and atrophy can only be applied when the enemy has lost all their physical armor.
