Seat of the Synod

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.

Roil Cartographer

Landfall — Whenever a land you control enters, you get {E} (an energy counter).
{T}, Pay six {E}: Draw three cards.

Aether Spike

Choose target spell. You get {E}{E} (two energy counters), then you may pay any amount of {E}. Counter that spell unless its controller pays {1} for each {E} paid this way.

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.

Pili-Pala

Flying
{2}, {Q}: Add one mana of any color. ({Q} is the untap symbol.)

Solar Transformer

This artifact enters tapped.
When this artifact enters, you get {E}{E}{E} (three energy counters).
{T}: Add {C}.
{T}, Pay {E}: Add one mana of any color.

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis to its owner's hand.

Puresight Merrow

{W/U}, {Q}: Look at the top card of your library. You may exile that card. ({Q} is the untap symbol.)

Generous Gift

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

Island

Horseshoe Crab

Morphling

{U}: Untap this creature.
{U}: This creature gains flying until end of turn.
{U}: This creature gains shroud until end of turn. (It can't be the target of spells or abilities.)
{1}: This creature gets +1/-1 until end of turn.
{1}: This creature gets -1/+1 until end of turn.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Bespoke Battlewagon

{T}: You get {E}{E} (two energy counters).
{T}, Pay {E}{E}: Tap target creature.
{T}, Pay {E}{E}{E}: Draw a card.
Pay {E}{E}{E}{E}: This Vehicle becomes an artifact creature until end of turn.
Crew 4

Razortide Bridge

This land enters tapped.
Indestructible
{T}: Add {W} or {U}.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Tune the Narrative

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

Farmstead Gleaner

This creature doesn't untap during your untap step.
{2}, {Q}: Put a +1/+1 counter on this creature. ({Q} is the untap symbol.)

Hallowed Fountain

({T}: Add {W} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Aether Hub

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

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Azorius Signet

Swords to Plowshares

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

Prairie Stream

({T}: Add {W} or {U}.)
This land enters tapped unless you control two or more basic lands.

Port Town

As this land enters, you may reveal a Plains or Island card from your hand. If you don't, this land enters tapped.
{T}: Add {W} or {U}.

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.

Omen Hawker

{T}: Add {C}{U}. Spend this mana only to activate abilities.

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.

Negate

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

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.

Thirst for Knowledge

Draw three cards. Then discard two cards unless you discard an artifact card.

Palladium Myr

Sol Ring

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Plains

Arcane Signet

Minamo, School at Water's Edge

{T}: Add {U}.
{U}, {T}: Untap target legendary permanent.

Counterspell

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Time Wipe

Return a creature you control to its owner's hand, then destroy all creatures.

Glimmer of Genius

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

Ancient Den

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.

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.

Minister of Inquiries

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

Reliquary Tower

Frantic Search

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

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.)