BLU is also extremely necessary for stupidly difficult NM's like this: http://wiki.bluegartr.com/bg/Abject_Kharoub

The second we engaged it we all ate a 1600 Tourbillion then he started picking people off with Thunderbolt and Bloodrake. Took multiple 2hrs to kill this thing, was harder than floor 100 boss. THis NM is also a gigantic time waster: http://wiki.bluegartr.com/bg/Nukku