Iron Wolves Doctrine's is used for crafting legendary set Asheara's Vestments.
Drop locations for Iron Wolves Doctrine:
Act II: Caldeum Sewers, Monster to hunt: Ningish
Act II: Dahlgur Oasis, Monster to hunt: Ssthrass
Asheara's Vestments set bonus:
2 set items equipped: + 100 Resistance to all elements
3 set items equipped: + 20% Life
4 set items equipped: Attacks cause your followers to occasionally come to your aid.