Mystery Booster 2

Conspiracy

(Start the game with this conspiracy face up in the command zone.)
You can't attack with an odd number of creatures.
Whenever you attack, double target creature's power until end of turn.

Rule with an Even Hand

Legendary Creature — Human Wizard

Familiar spells you cast have flash. (Bats, Birds, Cats, Dragons, Faeries, Foxes, Frogs, Imps, Lizards, and Spiders are familiars, as well as any creature with "Familiar" in its name.)
{T}: Add X {G} and each opponent loses X life, where X is the number of familiars you control.