In the manga[] In the original and R manga, the Fusion Material Monsters must exist on the field to be fused with "Polymerization", and once they are fused, they are still treated as separate cards for the purpose of specific card effects (most famously, "The Wicked Eraser", which treated the 3-Material "Arcana Knight Joker" as 3 cards and gained 3000 ATK)
If it's a Siege, it will still be exiled when the last defense counter is removed from it, and its controller may still cast it transformed without paying its mana cost
Be careful with the first effect of Red-Eyes Archfiend of Lightning as you can use it to bring out powerful Fusion monsters
Guardian: Leo Anderson - +2, an ally tutor effect
Temple of Malice isnt legal and you have early-drops that punish you for having lands enter the battlefield tapped, and this deck is very mana-intensive in general
Electivire ex Abilities