Your main priority is to thin the Deck. Wonder Wand is a good draw engine, and more than half your monsters are able to pull Gravekeepers out of the Deck.
Headman should always revive Spiritualist whenever possible, resulting in a Fusion.
Only make Supernaturalist with Spiritualist's effect. Do not use Magicalized Fusion.
Supernaturalist is strong enough that it won't be overpowered by any of Quattro's monsters. Necrovalley will complete your stall setup by allowing Supernaturalist's protection effect to go live.
Magicalized Fusion should be used to make Quintet Magician. You can do this at any point in the Duel if you want to use Quintet Magician as your staller, but the field wipe effect is most effective when used on the last turn.
On your final turn you should have Quintet Magician and Supernaturalist on board. Summon Vassal and use two Union Attacks and Fairy Meteor Crush on him.