Your opponent may have that one card that destroys you or your one is prized and you lose the game because you are playing only one one
You could win with Bontu's Monument or even make a tribal deck using Urza's Incubator
Legendary Creature - Human Samurai Color tag templates(None) Mardu Banner : Add , , or
Retreat: CC Weakness: P Resistance: None ------------------------------------------------------------------------------ Pidgey B38 - Common Type: Colorless Evolution: Basic Pokemon Level: 8 HP: 40 CC - Whirlwind (10) Effect: If your opponent has any Benched Pokemon, he or she chooses 1 of them and switches it with the Defending Pokemon
Its understandable, given just how hard it can be to really understand opportunity cost and to fully appreciate the selection Brainstorm gives us access to, but the technology of cost-efficient cards that shuffle pushed it over the edge
At the very least haste and lifelink probably mean you get in at least one big life swing before it breaks apart