Trample

At the beginning of your upkeep, sacrifice Deep Spawn unless you mill two cards.

: Deep Spawn gains shroud until end of turn and doesn't untap during your next untap step. Tap Deep Spawn. (A creature with shroud can't be the target of spells or abilities.)

Homarid enters with a tide counter on it.

At the beginning of your upkeep, put a tide counter on Homarid.

As long as there is exactly one tide counter on Homarid, it gets -1/-1.

As long as there are exactly three tide counters on Homarid, it gets +1/+1.

Whenever there are four or more tide counters on Homarid, remove all tide counters from it.

: Tap target green creature.

All lands are Islands in addition to their other types.

Other Homarids, Camarids, Cephalids, Nautilids, and Merfolk you control get +1/+1.

, Sacrifice a creature and a Swamp: Destroy target nonartifact creature. It can't be regenerated.

, Sacrifice a creature and a snow Swamp: Destroy target creature. It can't be regenerated.