I'd also like to point out that "Artifact" is a tremendously horrible name for this game:
The word "artifact" is tremendously generic and has no more connection to DOTA than to many other franchises.
In fact, if anything, it's arguably better connected to Magic: the Gathering. Having your title make people think of one of your competitors first is not a good move.
The word can be used to mean an error in a process (such as artifacts produced by a camera in photography) or something that is an irrelevant product of earlier times (such as saying that lives in video games are an artifact from when arcade games were the primary medium). Both definitions make the jokes at Valve's expense far too easy to make.