Marjhan

Marjhan doesn't untap during your untap step.
{U}{U}, Sacrifice a creature: Untap Marjhan. Activate only during your upkeep.
Marjhan can't attack unless defending player controls an Island.
{U}{U}: Marjhan gets -1/-0 until end of turn and deals 1 damage to target attacking creature without flying.
When you control no Islands, sacrifice Marjhan.

Sea Monster

Sea Monster can't attack unless defending player controls an Island.

Benthic Behemoth

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)

Giant Shark

Giant Shark can't attack unless defending player controls an Island.
Whenever Giant Shark blocks or becomes blocked by a creature that has been dealt damage this turn, Giant Shark gets +2/+0 and gains trample until end of turn.
When you control no Islands, sacrifice Giant Shark.

Ice Cauldron

{X}, {T}: You may exile a nonland card from your hand. You may cast that card for as long as it remains exiled. Put a charge counter on Ice Cauldron and note the type and amount of mana spent to pay this activation cost. Activate only if there are no charge counters on Ice Cauldron.
{T}, Remove a charge counter from Ice Cauldron: Add Ice Cauldron's last noted type and amount of mana. Spend this mana only to cast the last card exiled with Ice Cauldron.

Lightning Blow

Target creature gains first strike until end of turn.
Draw a card at the beginning of the next turn's upkeep.

Leviathan

Trample
Leviathan enters the battlefield tapped and doesn't untap during your untap step.
At the beginning of your upkeep, you may sacrifice two Islands. If you do, untap Leviathan.
Leviathan can't attack unless you sacrifice two Islands. (This cost is paid as attackers are declared.)

Tornado

Cumulative upkeep {G} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
{2}{G}, Pay 3 life for each velocity counter on Tornado: Destroy target permanent and put a velocity counter on Tornado. Activate only once each turn.

Volcanic Eruption

Destroy X target Mountains. Volcanic Eruption deals damage to each creature and each player equal to the number of Mountains put into a graveyard this way.

Death Match

Whenever a creature enters the battlefield, that creature's controller may have target creature of their choice get -3/-3 until end of turn.

Soul Barrier

Whenever an opponent casts a creature spell, Soul Barrier deals 2 damage to that player unless they pay {2}.

Didgeridoo

{3}: You may put a Minotaur permanent card from your hand onto the battlefield.

Cave Tiger

Whenever Cave Tiger becomes blocked by a creature, Cave Tiger gets +1/+1 until end of turn.

Grandmother Sengir

{1}{B}, {T}: Target creature gets -1/-1 until end of turn.

Aether Storm

Creature spells can't be cast.
Pay 4 life: Destroy Aether Storm. It can't be regenerated. Any player may activate this ability.

Ghost Hounds

Vigilance
Whenever Ghost Hounds blocks or becomes blocked by a white creature, Ghost Hounds gains first strike until end of turn.

Narwhal

Energy Storm

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Prevent all damage that would be dealt by instant and sorcery spells.
Creatures with flying don't untap during their controllers' untap steps.

Deep Water

{U}: Until end of turn, if you tap a land you control for mana, it produces {U} instead of any other type.