Simic's Charm-Fish

As an additional cost to cast this spell, you
may discard two cards.
If you discarded two cards in addition to
paying{1}{u} to cast Simic's Charm-Fish, tap target creature. It doesn't untap during it's owner's next untap step.
{1}{u}{u}{u}: tap each creature your opponent controls. They don't untap during their opponent's next untap step.