Planar Outburst

If the non-awaken part of the spell requires a target, you must choose a legal target. You can't cast the spell if you can't choose a legal target for each instance of the word “target” (though you only need a legal target for the awaken ability if you're casting the spell for its awaken cost).

If a spell with awaken has multiple targets (including the land you control), and some but not all of those targets become illegal by the time the spell tries to resolve, the spell won't affect the illegal targets in any way.

You can cast a spell with awaken for its mana cost and get only its first effect. If you cast a spell for its awaken cost, you'll get both effects.