Missions idea: Declare your main mission

I have an idea that I think would be cool for a future mission event. The "Declare Your Main" missions.

For the event temporary icons would be available for every champ.

The first mission would be to win a matchmade game with any champion icon equipped. Completing the mission would lock out all of the other temporary champion icons, make the the temp icon for the champ you used permanent, and unlock champ specific missions.

The missions that followed could be the same/similar to current and past missions but require play as your "declared" main.

The final mission would be to achieve mastery 7 with your "declared" main. The reward would be upgraded loading screen flair and mastery emote for your main.

Seems like it would be a fun and well received event, and not terribly difficult to do. Creating that many temp icons might be an issue, not sure on that aspect. Otherwise everything else would be pretty standard. Thoughts?