Not going to lie Mass Effect 3's Insanity difficulty was really kinda easy for me compared to the previous games, especially on release date
Although I think they upped it a bit when I came back a month or two later in my second playthrough
It's more difficult as a soldier.
Although tbh even that's pretty easy if you play your cards right
Nova in ME3 was pretty much made solely for the synergy with Charge, I think. The stumble animations and fair AoE damage is just for players who accidentally charge into the middle of a ginormous enemy group that in 2 would pretty much ruin you in a second flat lol
Carnage is an odd thing to have on such a biotics-focused class, although I suppose it's just there to combo with tech squadmates if you are so forced to have them.
Also yeah Shockwave is unfortunately a difficult beast to use. I'd save it for exploding Singularities that Liara throws out or something, and even then the limited range kinda gimps it on larger levels.
buff plz
Weapon-wise Lex is on the money. Max out a particular shotgun you like (Geth Plasma Shotgun is certainly a boss when you can get it), pick up Incendiary Ammo for it, and put in the Armor Piercing mod for extra juicy damage against your Atlases, Brutes and Banshees. Warp Ammo also works if you like setting up biotic splosions with your squadmates, although as a very tech player myself I prefer the damage-over-time that Incendiary gives. :3