Blizzard has stated that Mage Tower skins are not available in Remix. This means that this is likely a bug.
Word of the bug has spread quickly, most prominently via a Reddit thread by user Zackolite. While it seems to be fairly inconsistent, with some players reporting no luck or results, others also confirm that they received "werebear" and "sparklekitty" for simply completing the introductory quest and earning the new artifact in Dalaran. However, this does NOT seem to work consistently.
Mage Tower appearances have been a hot-button topic among the community since the clarification that they would not be included in Legion Remix, with many requesting that they return with the game mode. It remains to be seen what Blizzard may do to those accounts that were able to earn these highly requested forms in this way, especially since it doesn't seem obtainable by every player consistently.
