Amaqua, Gyruda's Whisper

Whenever a card with a tentacle counter on it is discarded, exile it instead. You may cast that spell
and you may spend mana as though it were mana
of any color to cast that spell.
{2}{u/b}{u},{t}, Pay 4 life: Target opponents reveals
their hand and chooses a noncreature, nonland
card that doesn't have a tentacle counter on it.
Put a tentacle counter on that card. That card
stays revealed for as long as it has a tentacle
counter on it.