Spontaneous Artist

When this creature enters, you get {E} (an energy counter).
Pay {E}: Target creature gains haste until end of turn.

Architect of the Untamed

Landfall — Whenever a land you control enters, you get {E} (an energy counter).
Pay eight {E}: Create a 6/6 colorless Beast artifact creature token.

Aetherworks Marvel

Whenever a permanent you control is put into a graveyard, you get {E} (an energy counter).
{T}, Pay six {E}: Look at the top six cards of your library. You may cast a spell from among them without paying its mana cost. Put the rest on the bottom of your library in a random order.

Peema Aether-Seer

When this creature enters, you get an amount of {E} (energy counters) equal to the greatest power among creatures you control.
Pay {E}{E}{E}: Target creature blocks this turn if able.

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).

Riku of Two Reflections

Whenever you cast an instant or sorcery spell, you may pay {U}{R}. If you do, copy that spell. You may choose new targets for the copy.
Whenever another nontoken creature you control enters, you may pay {G}{U}. If you do, create a token that's a copy of that creature.

Fabrication Module

Whenever you get one or more {E} (energy counters), put a +1/+1 counter on target creature you control.
{4}, {T}: You get {E}.

Lightning Runner

Double strike, haste
Whenever this creature attacks, you get {E}{E} (two energy counters), then you may pay eight {E}. If you pay, untap all creatures you control, and after this phase, there is an additional combat phase.

Empyreal Voyager

Flying, trample
Whenever this creature deals combat damage to a player, you get that many {E} (energy counters).

Aether Hub

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

Bristling Hydra

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

Maulfist Doorbuster

When this creature enters, you get {E}{E} (two energy counters).
Whenever this creature attacks, you may pay {E}. If you do, target creature can't block this turn.

Aethertide Whale

Flying
When this creature enters, you get six {E} (energy counters).
Pay {E}{E}{E}{E}: Return this creature to its owner's hand.

Confiscation Coup

Choose target artifact or creature. You get {E}{E}{E}{E} (four energy counters), then you may pay an amount of {E} equal to that permanent's mana value. If you do, gain control of it.

Era of Innovation

Whenever an artifact or Artificer you control enters, you may pay {1}. If you do, you get {E}{E} (two energy counters).
Pay six {E}, Sacrifice this enchantment: Draw three cards.

Longtusk Cub

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

Gonti's Aether Heart

Whenever Gonti's Aether Heart or another artifact you control enters, you get {E}{E} (two energy counters).
Pay eight {E}, Exile Gonti's Aether Heart: Take an extra turn after this one.

Janjeet Sentry

When this creature enters, you get {E}{E} (two energy counters).
{T}, Pay {E}{E}: You may tap or untap target artifact or creature.

Territorial Gorger

Trample
Whenever you get one or more {E} (energy counters), this creature gets +2/+2 until end of turn.

Consulate Turret

{T}: You get {E} (an energy counter).
{T}, Pay {E}{E}{E}: This artifact deals 2 damage to target player or planeswalker.

Aethertorch Renegade

When this creature enters, you get {E}{E}{E}{E} (four energy counters).
{T}, Pay {E}{E}: This creature deals 1 damage to target creature.
{T}, Pay eight {E}: This creature deals 6 damage to target player or planeswalker.

Whirler Virtuoso

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

Decoction Module

Whenever a creature you control enters, you get {E} (an energy counter).
{4}, {T}: Return target creature you control to its owner's hand.

Aether Theorist

When this creature enters, you get {E}{E}{E} (three energy counters).
{T}, Pay {E}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Aethersquall Ancient

Flying
At the beginning of your upkeep, you get {E}{E}{E} (three energy counters).
Pay eight {E}: Return all other creatures to their owners' hands. Activate only as a sorcery.

Servant of the Conduit

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

Glimmer of Genius

Scry 2, then draw two cards. You get {E}{E} (two energy counters).

Shipwreck Moray

When this creature enters, you get {E}{E}{E}{E} (four energy counters).
Pay {E}: This creature gets +2/-2 until end of turn.

Rogue Refiner

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

Woodweaver's Puzzleknot

When this artifact enters, you gain 3 life and get {E}{E}{E} (three energy counters).
{2}{G}, Sacrifice this artifact: You gain 3 life and get {E}{E}{E}.

Dynavolt Tower

Whenever you cast an instant or sorcery spell, you get {E}{E} (two energy counters).
{T}, Pay {E}{E}{E}{E}{E}: This artifact deals 3 damage to any target.