Farm Firefleas for Reserves or else Crystal Flash. Damage down on the thorns (6 hits suitless). Get shinecharge on the top-right ledge and use the last fireflea to interrupt.

Entrance condition:

{
  "comeInWithRMode": {}
}

Requires:

{
  "or": [
    "h_CrystalFlash",
    {
      "and": [
        "h_RModeCanRefillReserves",
        {
          "resourceMissingAtMost": [
            {
              "type": "PowerBomb",
              "count": 0
            }
          ]
        },
        {
          "partialRefill": {
            "type": "ReserveEnergy",
            "limit": 20
          }
        }
      ]
    }
  ]
}
{
  "or": [
    {
      "canShineCharge": {
        "usedTiles": 16,
        "openEnd": 0
      }
    },
    {
      "and": [
        {
          "doorUnlockedAtNode": 2
        },
        {
          "canShineCharge": {
            "usedTiles": 17,
            "openEnd": 0
          }
        }
      ]
    }
  ]
}
{
  "autoReserveTrigger": {}
}
{
  "partialRefill": {
    "type": "RegularEnergy",
    "limit": 21
  }
}
"canRModeSparkInterrupt"

Unlocks doors:

{"nodeId":2,"types":["ammo"],"requires":[]}

Dev note: FIXME: The last fireflea self-destructs and will drop a Large Energy right on top of Samus if full on PBs.