Budget Alternatives to Stormtide Leviathan

Slipstream Serpent $0.02 7U · Serpent This creature can't attack unless defending player controls an Island. Seismic Stomp $0.05 1R · Sorcery Creatures without flying can't block this turn. Magmatic Chasm $0.05 1R · Sorcery Creatures without flying can't block this turn. Trapped in the Tower $0.07 1W · Aura Enchant creature without flying Harbor Serpent $0.08 4UU · Serpent Islandwalk Sealock Monster $0.10 3UU · Octopus This creature can't attack unless defending player controls an Island. Seismic Elemental $0.12 3RR · Elemental When this creature enters, creatures without flying can't block this turn. Stoneshock Giant $0.18 3RR · Giant {6}{R}{R}: Monstrosity 3. Leviathan $0.21 5UUUU · Leviathan Trample Khod, Etlan Shiis Envoy $0.26 2U · Homarid Warrior All lands are Islands in addition to their other types. Over My Dead Bodies $0.30 4BB · Enchantment Creature cards in graveyards can attack and block as though they were on the battlefield, can blo... Island Fish Jasconius $0.34 4UUU · Fish This creature doesn't untap during your untap step. Form of the Dragon $0.45 4RRR · Enchantment At the beginning of your upkeep, this enchantment deals 5 damage to any target. Teferi's Moat $0.87 3WU · Enchantment As this enchantment enters, choose a color.