Use a Super to knock off the top Viola.

Requires:

{"ammo": {"type": "Super", "count": 1}},
"Morph",
{"heatFrames": 980},
{"or": [
  "Wave",
  {"obstaclesCleared": ["A"]}
]}

Exit condition:

"leaveWithDamage": {
  "enemy": "Viola"
}

Unlocks doors:

{"types": ["missiles", "super"], "requires": []},
{
  "types": ["powerbomb"],
  "requires": [{"heatFrames": 300}]
}

Dev note: Could save some heat frames by starting at 1 or 2, or by leaving the Viola just off camera, in the morph tunnel and gate glitch.