The Rogue Monastery guards the way to the East. The citadel is now being guarded by Andariel, who prevents anyone from chasing Diablo.
There's another, larger gateway leading through the Monastery; this is most likely the aforementioned way of the East, leading through the mountains and into the desolate lands of Aranoch. However the wooden portcullis is lowered.
After killing Andariel, it's presumably opened up, and the caravan led by Warriv is allowed to continue its journey to the East.
In Diablo II: Resurrected – Reign of the Warlock, the Outer Cloister may sometimes be terrorized; when it does, the Tamoe Highlands, The Pit, and Monastery Gate always also becomes terrorized. Four areas being terrorized at once may look impressive, but unfortunately Outer Cloister and especially Monastery Gate have low monster and unique density. Nevertheless, the Tamoe Highland's good density and ease of navigation, coupled with the Pit's evergreen status as a great farming zone, makes this set of terror zones popular.
Development
In earlier versions of Diablo II: Resurrected, the Monastery Gate can never be terrorized. This is of small loss as it is very small and has scant numbers of monsters.
