Youโre right in showing that stun isnโt exactly worth it for longer lasting CCs since it lasts short amount of time on players. On enemies, it lasts 3 seconds though.
Frost can be worth a try as not every player uses Frost Immune or Frost Resist but you will need a fair amount of elemental crit as Flawless Victory does reduce it by -10% (its additive) so youโd need 20% and it would act like 10% on flawless victory opponents or fast attacks.