Engineer build
Going heavy in the explosives will buff your nades and heavy in inventions will buff your turrets. Word of wisdom, turrets do not survive well and they do not benefit from your stats. But if you want to use them positioning is the golden key to their success.
What do you think goes well with grenade build? For pve and dungeons
Did you check the stickied, engineer build thread?
Poor craftsman blame their tools. Poor players blame their Engineer.