magic play landfall before land

[willie]

do u have to play landfall before you play land for it to work

[Void Elemental]

Landfall only triggers when a land comes into play under your control (or in the case of Rest for the Weary, if a land came into play under your control this turn). If a land comes into play under your control and nothing with landfall is in play under your control, there's nothing to trigger. In the case of Rest for the Weary, the landfall replaces the upper card text on resolution, so you can use something like Terramorphic Expanse while the Rest is on the stack.