Quote from aeonfluxYour Séance token has haste although Séance doesn't grant haste.
Quote from klducksI don't see a Giant Adephage token
Quote from Merestil Haye
The Commander tax applies only when you cast your Commander from the Command zone.The Commander tax only counts the number of times your Commander has been cast from the Command zone.
This applies to all Commander casting situations.
Remillo is responding to Kryptnyt's complex sequence of card moves by pointing out that, at any point where the Commander moves to either the Graveyard or Exile zone, its owner could stop the sequence dead by putting the Commander in the Command zone.
Quote from RemilloFor each time you cast it from the command zone, it costs 2 more to cast from the commander zone. If you cast it once, the next time it would be cast from the command zone, it would cost 2 more. If you cast it from your hand, reanimate it, etc, it would be for normal cost and would not count towards the cost additions.
With Kryptnyt's scenario, assuming you actually let it get destroyed or exiled and not return it to the command zone, it would only cost 2 to cast, assuming all of that ends up happening on the first time you cast it.
If your commander would be put into a Graveyard or Exile from anywhere, you can choose to put it back in to the command zone. So all of that would stop after the first Exile if the player were to choose that option.