Aether Hub

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

Sage of Shaila's Claim

When Sage of Shaila's Claim enters, you get {E}{E}{E} (three energy counters).

Brute Force

Target creature gets +3/+3 until end of turn.

Forest

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.

Giant Growth

Woodweaver's Puzzleknot

When Woodweaver's Puzzleknot enters, you gain 3 life and get {E}{E}{E} (three energy counters).
{2}{G}, Sacrifice Woodweaver's Puzzleknot: You gain 3 life and get {E}{E}{E}.

Highspire Infusion

Target creature gets +3/+3 until end of turn. You get {E}{E} (two energy counters).

Mountain

Larger Than Life

Target creature gets +4/+4 and gains trample until end of turn.

Might of Old Krosa

Target creature gets +2/+2 until end of turn. If you cast this spell during your main phase, that creature gets +4/+4 until end of turn instead.

Electrostatic Pummeler

When Electrostatic Pummeler enters, you get {E}{E}{E} (three energy counters).
Pay {E}{E}{E}: Electrostatic Pummeler gets +X/+X until end of turn, where X is its power.

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.

Built to Smash

Target attacking creature gets +3/+3 until end of turn. If it's an artifact creature, it gains trample until end of turn.

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).

Glassblower's Puzzleknot

When Glassblower's Puzzleknot enters, scry 2, then you get {E}{E}. (You get two energy counters. To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)
{2}{U}, Sacrifice Glassblower's Puzzleknot: Scry 2, then you get {E}{E}.