Dandân can't attack unless defending player controls an Island.

When you control no Islands, sacrifice Dandân.

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.

Kukemssa Serpent can't attack unless defending player controls an Island.

, Sacrifice an Island: Target land an opponent controls becomes an Island until end of turn.

When you control no Islands, sacrifice Kukemssa Serpent.

Marjhan doesn't untap during your untap step.

, Sacrifice a creature: Untap Marjhan. Activate only during your upkeep.

Marjhan can't attack unless defending player controls an Island.

: 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.

When Noggle Hedge-Mage enters the battlefield, if you control two or more Islands, you may tap two target permanents.

When Noggle Hedge-Mage enters the battlefield, if you control two or more Mountains, you may have Noggle Hedge-Mage deal 2 damage to target player or planeswalker.

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

When you control no Islands, sacrifice Sea Serpent.

When you control no Islands, sacrifice Skeleton Ship.

: Put a -1/-1 counter on target creature.

First strike

Vodalian Knights can't attack unless defending player controls an Island.

When you control no Islands, sacrifice Vodalian Knights.

: Vodalian Knights gains flying until end of turn.