Endless Detention

At the beginning of your upkeep, create a white
aura enchantment token called "Duolith" with
"Enchant creature: Enchanted creature cannot
attack or block" and attach it to target creature
that is not enchanted with an aura called
"Duolith." If you cannot attach that aura token
to a creature, sacrifice Endless Detention.
When Endless Detention leaves the battlefield,
exile all enchantments called "Duolith."