Adding cards like Archangel of Thune or Well of Lost Dreams turns your extra life into counters, card draw, and scaling threats
A hard case top loader provides a solid barrier to damage that could happen during the shipping process and gives your buyer some peace of mind ordering from you or your store
Dark Prophecy More resilient than the next few cards because its not a creature, Dark Prophecy is also harder to cast, harder to recur, and only triggers off your team
Though you can do better, these are worth running if you need a lot of redundancy or if you need mana dorks with activated abilities you can copy
Mirran Whenever you cast an artifact spell, create a 1/1 colorless Myr artifact creature token
If you want to be really mean, its even possible to remove all of your opponents lands using either Urza, Lord Protector or Planeswalker