Fensong Entrancer

{u/b}{u/b}{u/b}, {t}: Create a blue and black enchantment
aura token named Siren's Song and attach it to
target creature.
Whenever an enchanted creature an opponent
controls becomes tapped, gain control of it unless
its controller pays {x}, where X is the number of
enchanted permanents they control, if they do,
tap it and sacrifice all auras you control that are
attached to it.