You may be looking for the comic strip or the DVD extra.

The Planet of the Rain Gods was a planet inhabited by a primitive humanoid race who worshipped Rain Gods. The Eleventh Doctor and River Song visited this planet, where they were captured by two spear-wielding natives who intended to sacrifice them to the Rain Gods. They escaped when lightning frightened their captors, and returned to the TARDIS. (HOMEVID: Rain Gods)

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