If the full rules text of Invoke is in fact what is printed on Commune – “Invoke means play this card without paying its cost, then banish it” – then yes, you’d be forced to Invoke it. I think there’s a good chance though that the official rule will end up with the word “may” in the text (“Invoke means you *may* play…”), in which case when it triggered you could decide to do nothing and wait for it to trigger again later.