There are 3 apprentice placeholders for Chancellor Mardis, in separate rooms on the same floor. Same elevation as the garden and the mission NPC.
1930, -30, 438 (large central room, south)
2305, -130, 438 (circular room, north, east) - no adds in this room
2305, 70, 438 (circular room, north, west)
If you are hunting, the other names on this floor are Groundskeeper Areut, and Chief Recruiter Joceil.