Meanwhile I detoggle my GWP perk most of the times because Lae'z couldn't hit the broad side of a barn with it active.
75% when backstabbing someone is the most I can expect, but it's often below 50.
you need to bless your gwm master somehow. i do it with the bless ring you can sometimes buy from a goblin trader. drink potion with bonus action (because who cares about rogue) and you get blessed for one turn.
that increases your hit chance considerably.
alternativly bless your gwm with a cleric or with a certain arcane staff you can find in the underdark.
