You have 99 total cards to work with here, or 98 if you play with a partner commander
but if you exile a creature card and an Aura card, you can't cast that Aura targeting that creature
If the game state dictates that youre better off casting it (like Kozilek, Butcher of Truth) or keeping it in your hand (if the environment is currently hostile to the permanent type), then you have the option
It may be best to focus on mastering one specific mechanic, such as the Energy retrieval outlined above, before truly honing the scope of a deck
Add in Swarm Intelligence, and you'll be able to double the spell you cast from your hand and the spell you cast from your graveyard
Its also only your permanents, not all permanents unlike Homeward Path, so if you run theft effects in your own deck like Gilded Drake, Thieving Skydiver or Agent of Treachery , those effects will not end with Brand