can I play Anvil of Earth when there is No terrain in play to destroy?
No Terrain Anvil of Earth?
A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
can I play Anvil of Earth when there is No terrain in play to destroy?
I'm guessing you mean "Discovering the Anvil of Earth"? Please don't forget to use complete card titles (bullet #2 in that link).
And all targeting in actions is required, so no, you can't play Discovering the Anvil of Earth if there's no Terrain (or enemy Personality) to target.
On: Anvil of Earth