so the purpose of the game here is to guess what HM thingy the OP is talking about.
He gave us 2 clues
- "very near to the end a boss knocks me from a platform to a lower platform"
- and he didn't seems to have died instantly.
So, at first i thought about malgus but i believe you died instantly if you are bump
The second boss of lost island bump too, but can you survive, is there a lower plateform?
My best guess would be the 2nd to last boss of the esseles.
If it's Esseles all he has to do is remove himself from the group and he will be booted from the instance.