Mutant Marsh

When Mutant Marsh enters the battlefield, return a basic land you control to its owners hand. Then search your library for a basic land card and put onto the battlefield tapped. Then shuffle your library.
{t}, Sacrifice Mutant Marsh: Search your library for a basic land card and put it onto the battlefield tapped. Then shuffle your library.
Fetid gases bubble up amongst a profusion of riotous plantlife.