Greenbelt Rampager

When Greenbelt Rampager enters, pay {E}{E} (two energy counters). If you can't, return Greenbelt Rampager to its owner's hand and you get {E}.

Whirler Virtuoso

When Whirler Virtuoso enters, you get {E}{E}{E} (three energy counters).
Pay {E}{E}{E}: Create a 1/1 colorless Thopter artifact creature token with flying.

Firebolt

Firebolt deals 2 damage to any target.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Harnessed Lightning

Choose target creature. You get {E}{E}{E} (three energy counters), then you may pay any amount of {E}. Harnessed Lightning deals that much damage to that creature.

Bristling Hydra

When Bristling Hydra enters, you get {E}{E}{E} (three energy counters).
Pay {E}{E}{E}: Put a +1/+1 counter on Bristling Hydra. It gains hexproof until end of turn.

Aether Hub

When Aether Hub enters, you get {E} (an energy counter).
{T}: Add {C}.
{T}, Pay {E}: Add one mana of any color.

Mountain

Island

Voltaic Brawler

When Voltaic Brawler enters, you get {E}{E} (two energy counters).
Whenever Voltaic Brawler attacks, you may pay {E}. If you do, it gets +1/+1 and gains trample until end of turn.

Rogue Refiner

When Rogue Refiner enters, draw a card and you get {E}{E} (two energy counters).

Escape to the Wilds

Exile the top five cards of your library. You may play cards exiled this way until the end of your next turn.
You may play an additional land this turn.

Forest

Longtusk Cub

Whenever Longtusk Cub deals combat damage to a player, you get {E}{E} (two energy counters).
Pay {E}{E}: Put a +1/+1 counter on Longtusk Cub.

Servant of the Conduit

When Servant of the Conduit enters, you get {E}{E} (two energy counters).
{T}, Pay {E}: Add one mana of any color.

Attune with Aether

Search your library for a basic land card, reveal it, put it into your hand, then shuffle. You get {E}{E} (two energy counters).