2017-11-17 : Nimbus Maze's last two abilities check the subtypes of lands you control, not their names. You can activate the appropriate abilities as long as you control a land with the corresponding subtype, Plains or Island. Most nonbasic lands don't have basic land types, even if they produce colored mana. For example, Nimbus Maze itself is neither a Plains nor an Island, while Hallowed Fountain is both.