Can Orcust be played without Mermaid for the event?

I recently got all of the orcust URs from the new pack and I have the deck and I'm learning it.

I was planning to use it on the event but noticed Mermaid is banned. And in the combo videos I have watched it is a part of the combo. Can it be replaced?

Will the deck even be good without Little Knight or Apo? Or just replace Little Knight with Unicorn?