Now, that was both fun and silly. And way too easy.

Would a fire spread that fast ? Perhaps the tent was doused with a gasoline like substance, but then wouldn't the Khals smell it ?

And some eight big strong men wouldn't be able to break apart a wooden door, while one risks the flames and strangles an arrogant slave ?
Also, another drop in the quality of writing, where the repeated threats of rape felt as modern as a third wave feminist facebook forum.

Enough about that.

So... who do think Arya will eventually assassinate or try to assassinate ?
I vote Daenerys.
Logically, since Daenerys has been this unstoppable force, her enemies whether in Westeros or Eassos should fall back to good king robert's playbook and hire the Faceless Men.