Lure a Mella from the right by breaking the speed blocks or using Morph. Then manipulate it to go high enough to be used in the left doorway. Raise the Mella up to just below the door's ledge then climb up to the door. Then the Mella will start moving upward, which means it comes at you partially blind. Getting it to reach the door, and not just short of the door is the hardest part. If it drops below the camera it will be necessary to go back down and raise it some more.

Requires:

"canManipulateMellas"
"canCameraManip"
"canBePatient"
"canTrickyJump"
{
  "or": [
    "SpaceJump",
    {
      "and": [
        "HiJump",
        "canSpringBallJumpMidAir"
      ]
    },
    {
      "and": [
        "canTrickyUseFrozenEnemies",
        {
          "and": [
            "HiJump",
            "canWalljump",
            "canSpringBallJumpMidAir"
          ]
        }
      ]
    },
    {
      "and": [
        "HiJump",
        "SpeedBooster",
        "canWalljump"
      ]
    }
  ]
}
{
  "or": [
    {
      "obstaclesCleared": [
        "B"
      ]
    },
    "Morph"
  ]
}

Exit condition:

{
  "leaveWithGModeSetup": {}
}

Unlocks doors:

{"types":["ammo"],"requires":[]}