# Building Better Decks: Mana Efficiency
In Runeterra, you are given three main resources to manage: your mana, and your cards, and your life total.
The last one might be the most intuitive: at the core of the game, once you run out of life, you lose. Because of this, a common beginner mistake is to place too much emphasis on life totals, for example playing cards like Decimate and Boomcrew Rookie just to do direct damage to their opponent. But it's quite rare for an Expedition game to just be a straight race where we directly attack each other's Nexii.
Where most games of Runeterra are actually decided are in the first category, using mana efficiently. With few exceptions, whoever is best able to spend their mana over the course of the game is going to be the one who wins. For example, if your 3-mana Scaled Snapper trades with my 1-mana Fleetfeather Tracker, then that exchange put me up 2 mana; I have more mana to spend on playing another unit or spell. I can use that to play a bigger unit than you can, or save it to unleash an expensive spell you can't answer.
Should have picked +0/+3!
In this article, I'll talk about how to evaluate cards based on their relative mana efficiency, and build an Expedition deck that takes this principle into account.
(Managing the second resource is called card advantage, and is also important but warrants its own discussion.)
# The Vanilla Test: Is this unit any good?
What does it even mean to use mana efficiently? Efficiency in the context of Runeterra is mostly about board presence: how big your units are, and what kind of abilities they have. To get a sense of whether our mana is being spent well, we can apply what's known as "The Vanilla Test" to the cards we are playing.