Lord Valentai wrote...
OK, I've finished ME2 twice as a soldier and once as an infiltrator. Now I want to try Adept or Sentinel (suggestions?)
My problem is that I try to use a power such as Incinerate and it doesn't lock onto the weak areas, and thus does no damage. I know I'm doing something wrong, so some help would be most appreciated! 
Adept for fun mode. Sentinel for serious business.
I'm playing an Adept on Veteran now, toying with Singularity. Hilarity ensues. Example - in Mordin's recruitment mission with the fans, I tossed a Singularity at some Vorcha Heavies up on the catwalk. Often, the fan blows them across the entire stage (killing them). But last night, one Vorcha had the bad luck of being blown into one of the pillars. He just kind of slammed into it, his arms wrapped around it Wile E. Coyote style, and just kept screaming.
But when I'm on Insanity and want to play through with zero deaths (I still haven't succeeded quite yet), I choose Sentinel. To be honest, with the Sentinel the key is his Assault Armour power, the others are really just like fun bonuses. In the situation you described on how powers don't lock to objects like the Reaper Core, the way I took care of it as a Sentinel is to rely on my Assault Armour to defend against the husks while I just shoot at it with my Viper Sniper Rifle.