i have a Daretti deck that she'd love
DI-FL's avatar
Rarity could NEVER stoop so low as to be a red mage! She'd be more of a blue/black artifact mage because how posh~

Also correction: Applejack? Mono-Green. What was I thinking, AJ wouldn't want to use them fancy majiks!
Nightmare Rarity might be Blue/Black
Rarity herself more likely mono blue...
as for Applejack, go big or go home!!
but you can do that with Blue/Green...
mystic snake with a Temur Sabertooth to return it to your hand works for a counterspell
add Murkfiend Liege to untap mana creatures and speed on to your endgame!
Kruphix for her commander maybe?
for an unending 'harvest' of mana!