Unlock Maraxus
Complete arcade mode with Volita to unlock Maraxus.
100% success rate. 

Unlock Mishra
Complete quest mode using a preset duelist and deck to unlock Mishra.
100% success rate. 

Unlock Volita
Complete arcade mode with Kuldan to unlock Volita.

Go to: Magic: The Gathering - Battlegrounds Info Page | nGaming Home Page.