I personally run my Krogan Shaman without Shockwave. Barrier specced for full durability/shield recharge. Warp specced for Detonate, Expose and Pierce. Krogan Berserker specced for Capacity, Headshots and Weapon Damage. Rage specced for Durability, Martial Artist and Pure Rage. Slap on a Wraith with Extended Barrel and Smart Choke. Warp things, and then headshot or melee them. Works wonders for me, personally.