When you can't find the cards you need to bounce them around for free lore and prizes, you should focus on your Resist cards and use Mouse Armor to give Resist to your vanilla cards like Prince Naveen and Lilo, allowing them to quest safely and forcing your opponent to overspend their resources to deal with them
If you exile a land card, you can't play that card
As a Legendary, it's not too easy to find, and TCGPlayer lists the current market value for Sisu: Divine Water Dragon at $31.96
Aside from being another step in the normalization of expensive Magic product, the fact that Final Fantasy is a Standard-legal set presents its own set of issues
its a land that helps budget mana bases and makes multicolor decks better in Pauper Cube
Below, I have some suggestions on which cards I would cut first, and next on the chopping block would be several one-drops