Hi, Grayewick the Fusionist here, back with a more compact version of my previous Extra Deck Eldlich Monarch deck list that I posted a while ago as per request of the user GreenION. I've done most of the explanations there when it comes to my choices and general thought processes there so feel free to take a look at it if you fancy at this link down here:
https://ygoprodeck.com/eldlich-extra-deck-monarchs-master-duel/
No significant changes into the deck with the exception of it being the deck size from a 60 card list down to just 45, which isn't that bad, all things considered. One thing that you might consider adjusting the ratios of since this is a significantly smaller deck is
Ehther, the Heavenly Monarch and
Erebus, the Underworld Monarch. I personally prefer having more Ehther than Erebus and drawing them both when going second and especially when going first. Drawing Erebus going second would be stronger, though you can just tinker the ratios to your liking. So, yeah that's pretty much it.