I've never used Orcust before, so, while i was searching for some models, i found that most decks was using a big scrap engine to mill cards and get advantage, but i want to start using "pure" Orcust.
The game starts when you send a Orcust monster to the grave, normally in the first turn you will send Orcust Knightmare or World Legacy - "World Wand".
In World Wand case you would be going to link summon Lib the World Key Blademaster that can give you a extender, go for this if you have a good hand with a lot of ways to keep putting bodies for you links.
If you send Orcust Knightmare to the GY and have a monster in your field ~activate Orcust Knightmare ~send World Wand from your deck ~Activate World Wand ~Summon your banished Orcust Knightmare ~Link into Galatea, the Orcust Automaton ~Activate Galatea effect ~put World Wand back in the deck and set a Orcust Crescendo. Orcust Crscendo is a omni negate. This is the only combo that i found that is consistently while playing but also i many times ended having to make a choice between Orcust Crescendo or Orcustrated Return to extend my combo.
But anyway, the deck is not as good like i thought, but is funny and the card desing is very unique.
The thing with instant fusion is that it DESTROYS the monster with means that if you have Dingirsu, the Orcust of the Evening Star in the end fase, you can Negate Instant Fusion destruction effect giving you El Shaddoll Winda that is a Summon Limit in monster form.
GLHF