There's an almost absurd amount of items with increase spell DC though. You can easily get to ~25-26 on a Wizard and even higher on a Sorcerer. So landing debuffs is definitely doable.
According to the WIki the Steel Watchers also have Advantage on Dexterity Saving Rolls though, that is pretty harsh.
But it shows how those custom Larian items and illithid powers lead to an arms race with almost every enemy in Act III having insane stats and/or the absurd Unstoppable buff to compensate.
And then you discover all ground based CC spells are bugged with static DC of 12 :'(
I haven't had this issue at all on either MC sorc or on Gale or Fuzzlump.
What I do notice is a lot of players are trying to multiclass their casters, maybe they are checking the incorrect DC under one of the multiclasses using a dumped stat or something.
