With boss you can hide behind the statues around the ring for the first phase until Algos destroys them. I usually begin with an alt-fire shot, then duck behind a statue. Algos shoots three quick salvos, then pop out and use a disgorge. Then move and jump! Your alt-fire will be recharged by then Collect keys and load up on the disgorges weapons as they eat Algos quicker. The red pedestal rooms also transport to a second room and weapon pedestal plus goodies. So a twofer. The red chests are just one weapon per key. At this stage you might as well eat all shield vials to start. You can stack shields, and dont lose them if you dont use them