Oboro, Palace in the Clouds

A blue source that refuses to stay gone. Ignore the bounce clause and this plays like an Island: it enters untapped, taps for one blue, and does nothing fancy. The second ability is the entire point. A land you can return to hand for a single mana is a permanent that cannot be permanently destroyed, because you hold it in response to land destruction and replay it next turn for nothing from hand. The same loop turns any "when a land enters" trigger into a reusable engine: drop Oboro, bounce it, drop it again, each cycle costing one mana and a land drop while the trigger fires every time. It can also pull mana back at instant speed ahead of a board wipe that hits lands, or simply hide from targeted destruction by sitting in your hand. The cost is honest and self-limiting: every bounce eats a mana and ties up a land drop you might rather spend elsewhere, so the insurance is real but you pay for it whether or not the threat ever arrives. For a deck that wants a blue source it can never lose, or one built to abuse a landfall trigger as an engine, that price is worth paying. Note the abilities work only on the battlefield; discarded or milled, it lies in the graveyard like any other land, with no way back on its own.