Would like to have some help making the deck better.
Anyway, the best going first board is Mithra - tribute for Thestalos - Mithra effect for an extra tribute summon and tribute Thestalos for Erebus (shuffle a card from hand), send Pantheism and anything (preferably The Prime) then banish Pan for two domains and a Tenacity if you have another monarch in hand or an Erupt if you don't. This rips two cards and establishes what I call 'The Monarch Lock'. Domain with a Monarch locks out of extra deck, and if you have a majesty's then you also get a monster effect lock. You can also just use Erupt as your monster effect lock. Most of the time, the extra deck lock can really shut down some decks and if it doesn't, game two you can side for something like sphere mode or another Caius the mega monarch.
This may sound confusing but trust me this deck is pretty simple to understand.
Again, any suggestions are appreciated.