Phases 1: Zig zagging cube snake
During this stage youll want to be moving away while attacking it. It does small gradual hops at you and will eventually catch up. They are preset distances so its easy to judge when it will finally reach you. When it is one hop away simply tap boost to get outside of its range. Repeat until the next phase.

Phase 2 - Red cube lines
This is the beginning of the trouble. To avoid dying in this phase simply stay calm and watch the red groupings. Try and stay between the lines and attack them for as long as possible. Once youre blocked in by red lines and one appears on you, tap boost to the left to reach safety. It will take a lot of patience and a steely resolve to not accidentally hit the lines, or boost too early/late.

Phase 3 - Hydra looking cube w/ orb attacks
This is a very easy phase to do wrong. The farther away you are from the hydra, the harder it will be. Try and get pretty close to it and be at the top or bottom of the screen. Once it fires begin moving up/down immediately to dodge the grouping and narrowly find the opening. Rinse and repeat until phase 4.

Phase 4 - Zig zagging cube snake + orb attacks
You will want to do a mixture of the burst dodging and aggressive attacking. If you have multiple lives you can actually boost into an opening at the top or bottom of the snake and safely attack it, without the risk of dying to the orbs. This is actually the safest way to kill it for Phobos because of his slow move speed. For the other two you can kite endlessly and just dodge.