They all fail the saves, and the Fighter has Bardic inspiration now.
But you thought wrong on the falling bit...
Combat
So Hypnotic Pattern charms, and incapacitates them and reduces their speed to zero... and as they lack the ability to hover (they have the flight speed of a Vrock, and it lacks the Hover trait), they then fall 30' taking 3d6 (12) bludgeoning damage each (which also wakes them out of their stupor). They are no longer subject to the charmed or incapacitated condition and can move as normal, but are however now Prone.
It's also now the Trolls turn!
Before I do that though, I just realized I skipped the Rogue this turn.
Ill let her take her turn before the Trolls.
Yep, should have asked how they're flying. Thought about it after, oh well.