Difficult terrain while flying

I am playing a very specialized character. The goal is to use Precipice Strike with arcane trickster surprise spells feature. Since being on the ground naturally puts me at greater risk, I was wondering what ways were open to me to count as being in difficult terrain, hopefully ones that can be quickly turned on/off.

For more information I am in a gestalt game where I am a wizard rogue who then levels up in arcane trickster and magus. This links to questions Ive asked in the past about sneak attack damage on spells.