I am not completely sure but I believe that I heard Yaviks (aka the Rider) speking [b]russian[/b] during her boss-fight. She tends to shout a few lines when being attacked or boosting her pike, which sound extremely similiar to russian words for "[i]onwards![/i]", "[i]faster![/i]" and "[i]yes![/i]".
This makes pretty much no sense I think, unless Rider is somehow related to Rasputin maybe? I doubt that. Though it was funny noticing anyway!
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Bungie has always constructed their alien languages this way. Words in various Earth languages distorted, slowed down or backwards. And then there's Grunts, who scream in perfect English, "This one's for your Mama!"