From character level 50 you can find the 13 shards of the magic mirror on tavern quests. Shards will be added to your portrait automatically.

Magischer Spiegel

The more shards you found, the more difficult finding another shard becomes.

After finding and activating all 13 shards you avatar changes back to normal. Now you can fight in the arena or dungeons while being on a quest or being on a city guard shift..