Spell inconsistencies on your own hexproof creatures

stikxs

So I have Striped Riverwinder and Shanna, Sisay's Legacy out, both hexproof, and both the only creatures on the battlefield. I had Turn to Frog and Hostile Deserts in my hand. I can pop either of my creatures with frog and kill them, but I can't use the desert to buff them. One of those seems wrong.

DBJones

Being able to target your own hexproof creatures is correct (they even recently fixed it so you could target ones stolen with temporary effects like Willbreaker). I'm guessing the issue is Hostile Desert, maybe it doesn't cast if you have no deserts in your graveyard?