Efreet of Sundown's Glare
Creature - Efreet
Whenever you cast an instant or sorcery spell, Efreet of Sundown's Glare deals 2 damage to each player.
"'Where is your domain, o great lord?' I asked, and the man who was not a man smiled like embers beneath dark coals. 'My sultanate is the last red beam as the sun crosses the horizon. My palace is made of the long shadows and my courtiers are the stars that dare to peek through.'" - Arshia
4/2

Princes' Truce -
Sorcery
As an additional cost to cast this spell, tap three untapped creatures you control.
You gain 13 life.

Arshia, Storyteller
Legendary Creature - Human Nomad
, Exile Arshia: Players play a Magic subgame under the table, starting at 5 life and using their libraries as their decks. At the beginning of that game, put Arshia from exile onto the battlefield transformed. If you win the subgame, you gain an emblem with "You may cast enchantment spells without paying their mana costs." Exile Arshia at the end of that subgame. You may only activate this ability from any card named Arshia, Storyteller once per game.
2/2

Arshia, Eternal in Fable
Legendary Planeswalker - Arshia
: Exile the top card on your library. You may play that card this turn.
: You may put an Aura card from your hand onto the battlefield.
: Arshia deals 5 damage to any target and you gain 5 life.

I like this game, but I'm really not a fan of some of the planes thrown in at the end of the list, especially when they're all one after the other.

Brass Squadron
Artifact Creature - Construct (U)
Brass Squadron doesn't untap during your untap step.
At the beginning of your upkeep, you may sacrifice another artifact or creature. If you do, untap Brass Squadron and put a +1/+1 counter on it.
3/3

Yeah I might cull some planes from the list after the first run through. Rabiah is one candidate. Which other ones have been too hard?

Thief's Cave
Land
: Add .
, , Sacrifice ~: Create two colorless Treasure artifact tokens with ", Sacrifice this artifact: Add one mana of any color."

I think everything Vryn on is too thin. All we know about Regatha is that there is Keral Keep and a city where the Order of Heliud comes from. Rath has a little more but it's a part of Dominaria now. Ulgrotha is Worse Innistrad.

Now: Worse Innistrad

Fugitive Speaker
Creature - Human Cleric
When Fugitive Speaker dies, exile it. When you do, return a creature card with power 2 or less from your graveyard to your hand.
"The Serrans would rather destroy us than entertain that we need not bid farewell to the dead."
2/1

I mostly agree with neru. I think speculating on Vryn and Regatha can be interesting, but I wouldn't be upset if they were removed. Rabiah, Ulgrotha, and Rath are my least favorites. Shandalar I could live without, but I guess it's a decent place for generic fantasy designs so maybe keep it in.

The Endless Marjhan
Legendary Creature - Serpent (M)
Other creatures without flying get -X/-0, where X is the number of Islands you control.
Sacrifice a creature: Tap all creatures with power 0 or less.
7/7

Grandmother Sengir
Legendary Planeswalker - Ravi
As Grandmother Sengir enters the battlefield, destroy all creatures. Grandmother Sengir enters the battlefield with a loyalty counter on it for each creature destroyed this way.
: Target player gains an emblem with "At the beginning of your upkeep, put a -1/-1 counter on a creature you control and put a loyalty counter on a Ravi planeswalker you control."
: Reveal the top X cards on your library. You may put a card with converted mana cost X or less into your hand. Exile the rest and you lose 1 life for each card exiled this way.


ETA: Maybe we cut out those minor planes and it goes Fiora, then one round that is:

• Free For All using any of the minor planes (repeats allowed)
• OR the same minor plane for all the cards chosen by whomever does the white card
• OR a different minor plane for each card chosen by the card creator (no repeats)
• OR each card creator chooses the next one's minor plane (the creator for the Fiora land chooses the minor plane white)

then back to Mirrodin/New Phyrexia.

I think choosing the next person's plane could be interesting, but free for all might work best.

Anaba Ghost-Captain
Creature - Minotaur Spirit (U)
Reach
Other Minotaurs you control have "When this creature dies, it deals 1 damage to any target."
2/3

Prosperity of Great Wood
Legendary Enchantment
Mana doesn't empty from your mana pool.
At the beginning of your end step, if you have at least ten in your mana pool, create a 10/10 green Avatar creature token.
Feroz's ban slowed the flow of mana out of Great Wood and the forests feasted greatly on what pooled.

Feroz, Planeswalker
Legendary Planeswalker — Feroz
: Put a +1/+1 counter on target creature. It gains ", : Draw a card."
: Until your next turn, creatures can't attack target planeswalker or player unless their controller pays for each attacking creature.
: Target player gains an emblem with "You can't cast creature spells," and ": Create an X/X green Elemental creature token."

Chandler's Tools -
Artifact
, : Target creature you control fights target creature an opponent controls.

Planar Crypt
Land
: Add one mana of a color of a card in your graveyard.
Deep within the castle, Baron Sengir found the dwarves' secret.

Did I miss Mercadia or is that not a plane any more?

Rath


Liberated Sliver -
Creature - Sliver
Slivers you control have hexproof from enchantments.
2/2

Rootwater Savage
Creature — Merfolk Warrior
Whenever Rootwater Savage attacks, draw a card. At end of combat, if Rootwater didn't deal combat damage to an opponent, discard a card.
Deprived of light, the Rootwater will take it back.
3/2

I'm pretty sure it's still a plane. It just didn't get included in the list. Tack it onto the end, I guess?

Dauthi Slug -
Creature - Slug
Shadow
2 toughness: ~ loses shadow until end of turn.
2/4

Fake News -
Sorcery
Draw a card.
Buyback - Discard a card.
"Comrade Ogilvy, who had never existed in the present, now existed in the past, and when once the act of forgery was forgotten, he would exist just as authentically, and upon the same evidence, as Charlemagne or Julius Caesar." -George Orwell, "1984"