Since Leon couldn't use another spell while using Transfer, he wouldn't be able to rely on mithril to solve that problem. To move that monster to another world, Leon also would need a lot of mana, he didn't have enough on his own to do that, but he knew a way to make the spell succeed. It was by creating a massive container of metal and fill it with mana liquid.
"Spells only fail when there is something wrong with it and when the user doesn't have enough mana, so that should work."
Transporting that huge turtle to Ilyana's world wouldn't be possible since she was filling the world as a whole with her elementals. However, he could create the mana liquid there and then move it using the purple crystal. It could transport everything that was touching him, after all.
"That sounds a lot of work, do you want a hand?" Ilyana asked after hearing Leon's plan.