Stormwater Behemoth

Delve (Each card you exile from your graveyard
while casting this spell pays for {1}.)
When Stormwater Behemoth enters the battlefield, tap up to X creatures, where X is the
amount of mana used to cast Stormwater
Behemoth paid with delve. Those creatures don't
untap during their controller's next untap step.
"It guards the water with power and magic, any who
dare sail over its home disappear."