Wrath of the Skies

You get X {E} (energy counters), then you may pay any amount of {E}. Destroy each artifact, creature, and enchantment with mana value less than or equal to the amount of {E} paid this way.

Eddytrail Hawk

Flying
When Eddytrail Hawk enters the battlefield, you get {E}{E} (two energy counters).
Whenever Eddytrail Hawk attacks, you may pay {E}. If you do, another target attacking creature gains flying until end of turn.

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.

Orderly Plaza

Orderly Plaza enters the battlefield tapped.
{T}: Add {W} or {U}.

Suppression Ray

Tap all creatures target player controls. You may pay X {E}, then choose up to X creatures tapped this way. Put a stun counter on each of them. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Suppression Ray // Orderly Plaza

Aethertorch Renegade

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

Volatile Stormdrake

Flying, hexproof from activated and triggered abilities
When Volatile Stormdrake enters the battlefield, exchange control of Volatile Stormdrake and target creature an opponent controls. If you do, you get {E}{E}{E}{E}, then sacrifice that creature unless you pay an amount of {E} equal to its mana value.

Static Prison

When Static Prison enters the battlefield, exile target nonland permanent an opponent controls until Static Prison leaves the battlefield. You get {E}{E} (two energy counters).
At the beginning of your precombat main phase, sacrifice Static Prison unless you pay {E}.

Wheel of Potential

You get {E}{E}{E} (three energy counters), then you may pay X {E}.
Each player may exile their hand and draw X cards. If X is 7 or more, you may play cards you own exiled this way until the end of your next turn.

Galvanic Discharge

Choose target creature or planeswalker. You get {E}{E}{E} (three energy counters), then you may pay any amount of {E}. Galvanic Discharge deals that much damage to that permanent.

Guide of Souls

Whenever another creature enters the battlefield under your control, you gain 1 life and get {E} (an energy counter).
Whenever you attack, you may pay {E}{E}{E}. When you do, put two +1/+1 counters and a flying counter on target attacking creature. It becomes an Angel in addition to its other types.

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}.

Aether Theorist

When Aether Theorist enters the battlefield, 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 of your library.)

Aether Chaser

First strike
When Aether Chaser enters the battlefield, you get {E}{E} (two energy counters).
Whenever Aether Chaser attacks, you may pay {E}{E}. If you do, create a 1/1 colorless Servo artifact creature token.

Karn's Bastion

{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Animation Module

Whenever one or more +1/+1 counters are put on a permanent you control, you may pay {1}. If you do, create a 1/1 colorless Servo artifact creature token.
{3}, {T}: Choose a counter on target permanent or player. Give that permanent or player another counter of that kind.

Consulate Surveillance

When Consulate Surveillance enters the battlefield, you get {E}{E}{E}{E} (four energy counters).
Pay {E}{E}: Prevent all damage that would be dealt to you this turn by a source of your choice.

Shielded Aether Thief

Flash (You may cast this spell any time you could cast an instant.)
Whenever Shielded Aether Thief blocks, you get {E} (an energy counter).
{T}, Pay {E}{E}{E}: Draw a card.

Tempest Harvester

When Tempest Harvester enters the battlefield, you get {E}{E} (two energy counters).
{T}, Pay {E}: Draw a card, then discard a card.

Mechanized Production

Enchant artifact you control
At the beginning of your upkeep, create a token that's a copy of enchanted artifact. Then if you control eight or more artifacts with the same name as one another, you win the game.

Tune the Narrative

Draw a card. You get {E}{E} (two energy counters).

Gremlin

Deadlock Trap

Deadlock Trap enters the battlefield tapped.
When Deadlock Trap enters the battlefield, you get {E}{E} (two energy counters).
{T}, Pay {E}: Tap target creature or planeswalker. Its activated abilities can't be activated this turn.

Electrostatic Pummeler

When Electrostatic Pummeler enters the battlefield, 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.

Panharmonicon

If an artifact or creature entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Voltstorm Angel

Flying
When Voltstorm Angel enters the battlefield, you get {E}{E}{E} (three energy counters).
At the beginning of combat on your turn, you may pay {E}{E}. When you do, choose one —
• Voltstorm Angel gains vigilance and lifelink until end of turn.
• Other creatures you control get +1/+1 until end of turn.

Conduit Goblin

When Conduit Goblin enters the battlefield, you get {E}{E} (two energy counters).
At the beginning of combat on your turn, you may pay {E}. If you do, another target creature you control gets +1/+0 and gains haste until end of turn.

Aether Revolt

Revolt — As long as a permanent you controlled left the battlefield this turn, if a source you control would deal noncombat damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.
Whenever you get one or more {E}, Aether Revolt deals that much damage to any target.

Crackling Falls

Crackling Falls enters the battlefield tapped.
{T}: Add {U} or {R}.

Rush of Inspiration

Draw two cards. Then discard a card at random unless you pay {E}{E} (two energy counters).

Rush of Inspiration // Crackling Falls

Consulate Turret

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

Aether Swooper

Flying
When Aether Swooper enters the battlefield, you get {E}{E} (two energy counters).
Whenever Aether Swooper attacks, you may pay {E}{E}. If you do, create a 1/1 colorless Servo artifact creature token.