Isamaru, Hound of Konda Like Kodama of the North Tree, the context of Kamigawa Standard (or even Kamigawa Block Constructed!) is essential for understanding the reputation surrounding Magic s long-time Goodest Boy
To play substitute cards in a tournament they must have an official Magic card back, clearly indicate the name of the card youre substituting, and you need to own the actual card
In extreme cases where life isn't an issue, you can even cycle through the entire deck to know your choices and then play knowing what is coming, while in situations where life is precious you can usually get by with minimal loss
Im not sure why Wizards thinks those pair so well with X-spells, but that gives you room to play cards like Corpsejack Menace and Herald of Secret Streams to make this hydra commander unstoppable
Thankfully, not every card in the entire Spellbook is that strong, but its still one hell of a mana rock