Chea, Friend to Maybe Too Many (MB2PC-) - Mystery Booster 2

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.)
: Add X and each opponent loses X life, where X is the number of familiars you control.