I normally avoid using shield lob as well. I only use it when gathering monsters or adds from around the room/area. Then flash to gain some enmity with all mobs. Otherwise i don't think it should be part of any enmity generation combo or dps combo. =] Its pretty situational, and nice to have sometimes. I have it on a macro with fast blade for easy access when a mob spawns far from me and i need to get its attention too.