The Infected Monk can be found locked inside a cell in the Cell Circle portion of the Catacombs area. Speaking with him, he asks you to put him out of his misery.
To do this, we need to activate the lever to his right – but there is no lever handle! This can be found on the opposite side of the Cell Circle inside a wooden door near a statue and a large decorative level (we need to pull this to open the arena for the boss fight with the Champion).
Now return to the Infected Monk’s cell and use the Lever Handle on the broken lever. This will open the doors. Kill the monk for 1,500XP and a Spell Point Shard . Enter the door to the right of the lever for a Shield (Buckler - Blocker) .