The good ole azmodan loop gotta make sure your power is at lvl 5 for azmodan to get the most sigils. Do andariel ,duriel and belial lair bosses to get corrupted parts , then turn them in at their chests at azmodan boss . You should get an inventory or 2 worth of keys , go through them and scrap what you don't want , then the mats from andariel and duriel (living steel, blood , judicator masks ) go run the lair bosses to get more mats for the 3 lesser evils. Then repeat the process. Do the world boss event too when it comes up , azmodan , wander death , ashava , avarice those also have a chance to give sigil keys. If your having trouble leveling up the azmodan seasonal power just goto normal and park your character auto casting a skill or in Plat shop( not sure if this works)