aaahhh, mission 6 lvl 79 flying raped me :/
one tactic to kill the bosses with mucho hp, make a main maze for normal mobs, they all die in there with enough uber plasma and uber sams, make sure that the 2 mob streams join so your sams hit all mobs with every rocket.
make a secondary maze with some freeze cannons and plasma towers behind the main maze, when the bosses get in there, just open the maze to the exits at the point opposite of where they are. sell a cheap vulcan tower, repeat when they are on the other side of the maze, etc. etc.
start early with building anti air cause it rapes you at the end.
and howdy morlog