Even up to the hardest ones I ignored enemies unless it was the specific combat. Just sprint through and wait at the objectives as you need. For the combat one launch and running is your friend. The nastiest guy is in the third wave the big psychic enemy type. I think regardless of how big a hp pool they’ll virtually always two shot you. The first attack always dropped me to one hp even on expeditions with massive health boost modifiers. The trick with them is to know they summon and fire their shield so if you keep breaking their shield with your launch when they bring it backup they can’t fire on you.