S1eth advised using the tag heart_sutra to tag the not-uncommon meme of Kasodani Kyouko saying "gyate".
It's my opinion that "gyate" is going to be the most common reference to the Heart Sutra in posted pics, though, and I suggest aliasing "gyate" to "heart_sutra" for the convenience of anyone who's noticed the Kyouko catchphrase but doesn't know its significance.
Also: would it be appropriate to add "heart_sutra" to the tag group:meme article under "catchphrases" (even though, technically, the Heart Sutra is not itself a catchphrase)?