It can't just stay undefined, so if Shellephant is going to be on the battlefield or something needs to know its power or toughness, you should activate the ability to define it
Where it fails is that this green instant wont protect you , but rather, only your permanents
A very small "Lightsworn" engine can be opted for, consisting of nothing more than "Charge of the Light Brigade" and "Raiden, Hand of the Lightsworn", just keep in mind that "Raiden" will eat up your Normal Summon and will not contribute to any further plays in the GY since he is a Warrior
Thats why weve put together this incredibly useful guide on how to build a Magic: The Gathering deck as a beginner
Similar to the previous build, Lightning Chidori and a second Gagaga Cowboy are crucial in the Extra Deck, I just havent been able to locate a copy before the tournament.