One of the most difficult bosses in Returnal is Ophion, which is faced at the end of the second act. Ophion cannot be harmed without first discovering its gimmick, which involves using a power that the player earned earlier in the game.
Ophion is faced at the end of the sixth Biome. The player should have access to the upgrade that lets them survive underwater, as well as the visor that lets them see the silver orbs that create platforms. As is the case with all bosses, preparation is key for Ophion. The player's chances of victory will be drastically increased if they come in with healing potions and items/Parasites that will let them survive a fatal blow. Ophion's attacks don't deal a lot of damage, but they tend to fill the arena, which means that a misstep will lead to a chunk of health being taken off.
The first tip for facing Ophion is keeping a safe distance. The player will never need to go in for melee attacks for this battle, so always stay as far away as from Ophion as possible. This will give the player as much time as possible to dodge attacks, as most of them come from Ophion's body. It's also worth keeping an eye out near the edge of the arena (the opposite end from Ophion), as health pickups can spawn.
Ophion's body cannot take damage on its own. The player needs to strike the silver orbs that are floating around its body, which will cause eyeballs to sprout all over Ophion's form. The player needs to shoot these eyeballs in order to damage Ophion. If the eyeballs disappear, then shoot the silver orbs to make them reappear. Ophion will fire massive volleys of blasts at the player throughout each phase, in a manner similar to an Ikaruga boss. Luckily, most of the blasts are slow-moving, so it's just a case of waiting for them to get close and dashing through them.
Ophion's deadliest weapons are its shockwaves and purple lasers. If one of Ophion's tentacles hits the ground, then it will create a shockwave that needs to be jumped over. The dark purple lasers used by Ophion cannot be dashed through, so the player needs to manually move around them. It's highly advised that the player bring in a weapon with a large AoE or a fast fire spread into this battle. The eyes and silver orbs are pretty large, but the player will be constantly moving around Ophion's fire, so a weapon that doesn't require a great deal of accuracy will make the fight a lot easier. Just focus on dodging Ophion's lasers and it should easily go down.
Returnal will be released for the PS5 on April 30, 2021.