Fatigue will cause (I think!) -1 to all rolls including attacks, and saves.
Also this will worsen every 4 hours after the 1st warning (?).
You sleep to cure fatigue.
There are items in BG and IWD that will stop this.. but the rest of your party is tired so not mush point.
One of the effects of Wild Magic Surge will also rest that Mage in particular.
HAIL AERIE!
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