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.
![Quicksilver Fountain [Mirrodin] | The Clever Kobold](http://thecleverkobold.com/cdn/shop/products/b4f2bf63-e3cf-4a58-86b7-f3bab3b90712.jpg?v=1574227172)
