Vanguard with Biotic Charge maxed out and power cool downs off. Fighting that one Spectre during the Shadow Broker DLC was one of my favorite vidya fights of all time like that, we both just teleported around the room firing at each other. That plus that one long(er) range, armor-piercing shotgun. Woo.
"No, Mama. You can bet your sweet ass and half a titty whoever put that hit on you already got the cops in their back pocket." ~Black Dynamite