Taking the west wing, go up the first set of stairs once in the wing (the are against the wall, forward and head upwards to the south (left). Once at the top youll see in front of you a stage like area, go up this and in the corner you'll see a platform that will take you to the courtyard.
In the courtyard, head to the southwest 2 portals (they look like short poles on either side of the steps), .. Facing the stairs it will be the oneon the right side (on the maps it will be marked B). This will take you to the area called the Greater Blizzard Tower. In this part of the map is the only area Ive seen the DRI's spawn.. just keep killing, it will spawn .. I got mine in the second area)