Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Quicksilver Fountain

At the beginning of each player's upkeep, that player puts a flood counter on target non-Island land they control of their choice. That land is an Island for as long as it has a flood counter on it.
At the beginning of each end step, if all lands on the battlefield are Islands, remove all flood counters from them.

Carpet of Flowers

At the beginning of each of your main phases, if you haven't added mana with this ability this turn, you may add X mana of any one color, where X is the number of Islands target opponent controls.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Choke

Islands don't untap during their controllers' untap steps.

Tsunami

Typhoon

Typhoon deals damage to each opponent equal to the number of Islands that player controls.