Inventive to keep playing featured game-modes?
I know, the big ones usually have icons a long with their event, but maybe create a reward(s) for the less 'event'ful ones.
Example:
Win 10 Featured Game Modes Matches Win 50 Featured Game Modes Matches Win 100 Featured Game Mode Matches Win 200 Featured Game Mode Matches Win 500 Featured Game Mode Matches
Each one containing an icon with the ladder being a silly/fun skin for Ziggs, since he's the game-mode mascot usually. All wins in ANY featured game-mode, including the big event ones, go towards the meta achievements.
Why do this? Because if anyone is like me, sometimes knowing I'm working towards an ultimate goal will make me play more and more until I reach it. In fact, I'd be playing some One-For-All right now instead of coming off of gaining 100 Gold in Hearthstone and making this forum post. True story!