The first category to look at is the most obvious one: spend X mana to cast a card, and when it enters the battlefield, you get Y energy
This means you can score up to 11 booster packs for most sets, and up to 35 boosters for Murders of Karlov Manor, Outlaws of Thunder Junction, Modern Horizons 3, and Duskmourn: House of Horror
This gives us what we call "tempo advantage." We'll be two steps ahead of our opponent by casting threats early and often, beating them down to 0, and winning while they still have expensive cards stuck in their hands
Mana-ramping is insanely powerful, and having a creature -- with all the benefits of the creature -- also double as a way to generate resources is really good
It plays offense and defense at the same time, and benefits from either position
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