Greenwheel Liberator : Creature (Elf Warrior), casting cost of one generic and one green mana, 2/1
Which background works best for a Laezel, Vlaakiths Champion energy deck
Contents: 9 Modern Horizons 3 Play Boosters 1 Modern Horizons 3 Collector Booster 1 Traditional Foil card with Bundle-exclusive alternate-art 15 Traditional Foil Basic Land cards (5 with Full Art) 15 nonfoil Basic Land cards (5 with Full Art) 1 oversized Spindown life counter 1 card storage box 2 reference cards Each Play Booster includes a combination of 15 cards of rarity Rare or higher and 36 Uncommon, 58 Common, and 1 Land cards
The reason for that one in particular was that some decks need answers to things like Moat, and also because it probably is the most old school card there is
Your final result should look like this
While not quite a proper mana doubler, its still a whole pile of extra mana when considering the cards low cost