Basilisk Collar

Equipped creature has deathtouch and lifelink. (Any amount of damage it deals to a creature is enough to destroy it. Damage dealt by this creature also causes you to gain that much life.)
Equip (: Attach to target creature you control. Equip only as a sorcery.)

Some patriars pay massive sums for exotic pets that can give their posh, predictable lives an edge of danger.