"Bard" is likely a counter/enemy of the void.

Or, at least, Rek'sai. Let's point out some facts:

• Riot's general champion release is "Bad guy first, good guy second". We've had rek'sai, so logically next comes....
• "Bard's" release is listed as The Wonder Above. Conversely, Rek'sai was listed as The Terror Below
• We have yet to see someone who speaks as a counter or a "good" version of the void, a being of benevolence and pure power far beyond the scope of mere mortals.

So, my guess is that "Bard" is of a race thousands of years old and sort of an omnipotent being that has only arisen because of the rapid void infestation that has overtaken Runeterra, Rek'sai's arrival the final catalyst to force Bard's hand....arm...tentacle....I have no clue what he/she gonna look like.

EDIT: Ok, been getting a lot of shit with the "Champion release villain first/hero second" point. Let me point out that it was originally Riot's plan of action, not my personal discovery, that went into making this point. As of late yes, they've begun to push that to the wayside. So take the first point with the grain of salt, as I am apparently using old information.