Just to make sure, when we take most of a monster's HP, we usually get the drop, right?
For example in Godwards, or Corporeal Beast, if we take most of its HP away, we get the drop, no?

Then I feel like Tormented Demons are an exception to this rule.
I'm aware that when we die, or leave them unattacked, they'll heal a part of their HP, but often I realize that even when I leave them with less than 10-20 HP, by dying or other means, if someone starts attacking them, it seems that they'll be getting the drop instead of me.

I can use a real example of dying when the Tormented Demon had probably less than 10 hp left, I came back as soon as possible (Teleport to GE for quick banking, then Ferocious Ring to Varrock Slayer Dungeon, then Tormented Demons) and as soon as I got there, the Tormented Demon I was killing was already getting killed, and after it died I didn't see any drop.

So I feel like they are excluded from the Most damage rule. Care to explain this, or perhaps fix this?