Surge Engine

Defender
{U}: This creature loses defender and gains "This creature can't be blocked."
{2}{U}: This creature becomes blue and has base power and toughness 5/4. Activate only if this creature doesn't have defender.
{4}{U}{U}: Draw three cards. Activate only if this creature is blue and only once.

Counterspell

Thrummingbird

Flying
Whenever this creature deals combat damage to a player, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Minister of Inquiries

When this creature enters, you get {E}{E} (two energy counters).
{T}, Pay {E}: Target player mills three cards.

Deranged Assistant

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Consulate Surveillance

When this enchantment enters, 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.

Multiform Wonder

When this creature enters, you get {E}{E}{E} (three energy counters).
Pay {E}: This creature gains your choice of flying, vigilance, or lifelink until end of turn.
Pay {E}: This creature gets +2/-2 or -2/+2 until end of turn.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

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.

Mindshrieker

Flying
{2}: Target player mills a card. This creature gets +X/+X until end of turn, where X is the milled card's mana value.

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.

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}.

Consulate Turret

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

Rex, Cyber-Hound

Whenever Rex deals combat damage to a player, they mill two cards and you get {E}{E} (two energy counters).
Pay {E}{E}: Choose target creature card in a graveyard. Exile it with a brain counter on it. Activate only as a sorcery.
Rex has all activated abilities of all cards in exile with brain counters on them.

Horseshoe Crab

Shielded Aether Thief

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

Voltaic Construct

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Aetherling

{U}: Exile this creature. Return it to the battlefield under its owner's control at the beginning of the next end step.
{U}: This creature can't be blocked this turn.
{1}: This creature gets +1/-1 until end of turn.
{1}: This creature gets -1/+1 until end of turn.

Electrostatic Pummeler

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

Aetherstorm Roc

Flying
Whenever this creature or another creature you control enters, you get {E} (an energy counter).
Whenever this creature attacks, you may pay {E}{E}. If you do, put a +1/+1 counter on it and tap up to one target creature defending player controls.

Aethergeode Miner

Whenever this creature attacks, you get {E}{E} (two energy counters).
Pay {E}{E}: Exile this creature, then return it to the battlefield under its owner's control.

Grateful Apparition

Flying
Whenever this creature deals combat damage to a player or planeswalker, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)