this is one the cheap deck you can make.
the key here is to fill grave and extra with metalfoes monster while summoning metalfoes fusion monster. summon alkahest is high priority. mithrilium for recrycling and to combo with vanisher so you can banish opponents monster every turn. necro fusion and super polymerization is the best disruption and board breaker to control opponent's field.
metalfoes also a deck that can make a OTK combo if its not disrupted. but it has a weakness againts mass removal backrow. so make a defense board with metalfoes counter, metalfoes fusion, and bismugear is the best to comeback at the next turn.
you can also mixed it later with fluffal, prank, eldlich, true draco, tenyi, or inzektor if you are bored with pure metalfoes... but if you new to this archetype, i recommend you to play pure first due to many rulings that can help you gain advantage.