Must use at least 1 Rock-type monster as Fusion material.
You are most likely required to use Polymerization to Fusion Summon, therefore you can use these cards to support your Fusion actions. Fusion Recycling Plant can recycle 1 fusion material monster to your hand, and also search for Polymerization from your deck. King of the Swamp can be treated as 1 fusion material required for Fusion Summon, and at the same time it also can be used to search 1 Polymerization from your Deck. Fusion Sage can search 1 Polymerization from your deck. Defusion is a powerful follow-up card when you attack with your Fusion monster, as it can dissolve the Fusion monster to resummon the Fusion materials from your Graveyard, enabling you more attack options. Fusion Reserve allows you to add 1 of the Fusion materials listed on the Fusion monster to your hand, and add 1 Polymerization from your Graveyard to your Hand.