Slith Firewalker

At the beginning of the end step, if you control no creatures, sacrifice this land. T: Add one mana of any color.

Serra Avatar's power and toughness are each equal to your life total. When Serra Avatar is put into a graveyard from anywhere, shuffle it into its owner's library.

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

White creatures get +1/+1.

G, T, Sacrifice this creature: Destroy target enchantment.

Whenever this land becomes tapped, it deals 1 damage to you. T: Add one mana of any color.

Volcanic Hammer deals 3 damage to any target.

Target creature gets +3/+3 until end of turn.