So far, Li Pu has fused quite a few cards and summarized a lot of experiences.
Generally speaking, when two cards are fused, one serves as the main body, and the other as the attachment.
The main body retains a significant portion of itself, while the attachment becomes a mere add-on.
But which one becomes the main body and which one becomes the attachment is not something he knows before previewing.
This is unrelated to the strength of the fantasy creature entities, unrelated to the order, unrelated to the card's rank or score.
He calls this situation "stubbornness."
The more stubborn a card is by itself, the more likely it is to become the main body.
Of course, there's another less common situation.
That's when the newly fused card doesn't have much to do with the two original cards, like a brand new existence.
However, this scenario is quite rare, and so far, he's only previewed it a few times, all resulting in dud cards.
