Joostmod/SA-X

The SA-X (Samus Aran-X) is a post- boss added by the Joostmod. It is summoned by using an anywhere. The boss consists of three phases.

Behavior
Phase 1

The SA-X approaches the player while firing ice beams at them. These beams inflict the Chilled, Frostburn and debuffs on-hit. The SA-X can charge these shots to deal more damage. It can also fire Super Missiles, often as a follow up to freezing the player. In Expert Mode, Super Missiles will remove the player's flight time. Lastly, the SA-X will occasionally morph into a ball and lay a Power Bomb. During this phase the SA-X will fire in the predicted path of the player.

If the target player goes too far away, SA-X will continuously space jump towards them. While space jumping, the SA-X takes 50% less damage from all weapons and cannot receive critical hits.

Phase 2

In its mutated form, the SA-X can throw a dash punch, jump to create shockwaves upon landing, fire a barrage of missiles and spit acid at the player.

The Acid Spit attack is short-ranged and spits 8 globs of acid. The acid globs splash into droplets that deal half damage. Both of projectiles inflict the Poisoned and debuffs. The Missile Barrage attack is medium-ranged and fires 3 volleys of 4 missiles in a circular motion around it. The Missiles are affected by gravity and will fall down and explode. The Dash Punch attack is far-ranged and fires a volley of 5 missiles. The Dash is faster the further away the SA-X is from the player. The Jump attack is far-ranged and creates shockwaves upon landing. The shockwaves travel quickly across solid tiles. This attack will track the player, attempting to land on them.

When far from the player, the SA-X will prioritize using the Dash Punch or Jumping. In Expert Mode, the Mutated SA-X's missiles and melee strikes disable the player's flight abilities until they land.

Phase 3

The SA-X in its "true form" flies directly towards the player. The core periodically opens its 'eye' to fire charged ice beams that inflict Frostburn, Chilled, and. It will occasionally spin and fire uncharged ice beams in all directions. It may also summon a random X Parasite.

Hitting the SA-X in the 'shell' deals 50-80% less damage and cannot deal critical hits; X Parasites will be summoned based on the damage received. Hitting the SA-X in the 'eye' will deal a guaranteed critical hit, but for standard damage. Beam-type weapons like the Last Prism cannot benefit from hitting the SA-X in the eye. They will always deal reduced damage as if they hit the shell.

During this phase, hitting the SA-X in the shell will prompt the following message, "It seems hitting it in the 'shell' isn't very effective...".

Trivia

 * SA-X is the main antagonist in Metroid Fusion.
 * The X Parasites have different affects in Metroid Fusion as instead of being killed, they are picked up because of a metroid vaccine that's been applied on Samus.