Genbai of Mikokoro1UU
Legendary Planeswalker - Genbai
+2: Untap target Island or Spirit. That permanent gains hexproof until your next turn.
-4: You may cast an instant or sorcery card with converted mana cost equal to or less than the number of Islands you control from your graveyard without paying its mana cost. Exile it as it resolves.
-10: Reveal your library. Put all Island cards revealed in this way onto the battlefield, then shuffle your library. Islands you control become 3/3 blue Spirit creatures with flying and hexproof in addition to their other types.
Next: A non-Gideon who does "physical combat" of some form.
Palladia-Mors, World Devastator2RGGW
Legendary Planeswalker - Mors
+3: You gain 4 life. Palladia-Mors, World Devastator deals 2 damage to up to one target creature.
-4: You may put a creature card from your hand onto the battlefield with a +1/+1 counter on it. It gains haste and vigilance. Sacrifice that creature at the beginning of your next turn.
-15: You get an emblem with "Creatures you control have indestructible. At the beginning of your upkeep, each creature fights another target creature."
Next: A Huatli or Samut outside of her home plane.
Skhorr, Fire Enemy2BR
Legendary Planeswalker - Skhorr
+1: Skhorr deals 2 damage to each player. Each player dealt damage in this way draws a card.
-3: Skhorr deals 3 damage to each creature and each other planeswalker.
-5: Exile your hand. Put two time counters on each nonland card exiled in this way and each of them that doesn't have suspend gains suspend.
Next: Nongreen, nonwhite planeswalker who somehow manipulates or deals with enchantments.
Constance, Fist of Her Homeworld3GW
Legendary Planeswalker - Constance
+2: Create a 0/4 green Treefolk Wall creature token with defender and reach.
-4: Until end of turn, creatures you control have "T: This creature deals damage equal to its toughness to target creature."
-10: Search your graveyard, hand, and/or library for any number of creature cards with defender and put them onto the battlefield. You get an emblem with "Creatures you control can attack as though they didn't have defender and assign combat damage equal to their toughness rather than their power." If you searched your library in this way, shuffle it.
Next: A monoblue planeswalker with a +4 loyalty ability.
The Maze-Runner-as-'walker challenge was technically never answered (Aurelia was guildmaster, not runner) so I'm gonna do that simultaneously with this. The unique win condition is luck (similar to Chance Encounter and Amulet of Quoz).
Ral, Chained to Melek3UR
Legendary Planeswalker - Ral
+2: Until end of turn, up to one target creature loses all abilities and becomes a red Weird with base power and toughness 0/1.
-3: Until end of turn, whenever a creature an opponent controls is dealt damage, draw a card and Ral, Chained to Melek deals 1 damage to that creature's controller.
-8: Flip five coins. If all five coins come up heads, Ral, Chained to Melek deals 999,999 damage to each opponent. Otherwise, for each coin that comes up heads, search your graveyard and/or library for an instant or sorcery card, reveal it, and put it into your hand, and create an X/X blue Weird Avatar creature token, where X is that card's converted mana cost. If you searched your library in this way, shuffle it.
Next: A Karn or Ugin with colored mana somewhere on the card.
Legendary Planeswalker - Saheeli
+1: Up to one target creature gets +1/+0 and gains haste until end of turn. Saheeli, Overclocker deals 1 damage to each opponent.
-1: Create a 3/1 colorless Wolf Construct artifact creature token with haste and trample. Exile it at the beginning of the next end step.
-7: You get an emblem with "Whenever an artifact creature you control attacks, it gets +X/+0 and gains trample until end of turn, where X is twice its power."
Next: A Dragon on Innistrad. Can be Bolas, Ugin, or someone new.
Ajani and Gideon, Back to Back4GWWW
Planeswalker - Ajani Gideon
+1: Creatures you control get +2/+2 until end of turn.
0: Until end of turn, Ajani and Gideon, Back to Back becomes a 9/9 Human Cat Soldier creature with indestructible that's still a planeswalker. Prevent all damage that would be dealt to them this turn.
-2: Until the beginning of your next upkeep, creatures you control gain double strike, no more than one creature can attack each combat and no more than one creature can block each combat, and each player must attack or block with creatures each combat if able.
-11: Target creature gets +20/+20 until end of turn.
Freyalise, Architect of the Mending2GG
Planeswalker - Freyalise
+3: Sacrifice a land. If you do, add BRG to your mana pool.
+1: Up to one target creature gets +2/+2 and gains haste until end of turn.
-1: Exile target enchantment or planeswalker.
-13: Target opponent gets an emblem with "You can't play lands, can't untap more than two lands during your untap step, and can't activate abilities of nonland permanents."
Nissa, Force of Nature2GGGG
Planeswalker - Nissa
+2: You may put a land card from your hand or graveyard onto the battlefield.
-2: Untap all basic Forests you control.
-4: Create a legendary 8/8 green Elemental creature token named Ashaya in Fury with trample.
-12: Reveal your library. Put all creature and land cards revealed in this way onto the battlefield. Then shuffle your library.
Elspeth, Bound to Godsend1WW
Planeswalker - Elspeth
+1: You and permanents you control gain absorb 1 until the beginning of your next turn. (If damage would be dealt to you or a permanent you control, prevent 1 of that damage.)
-3: Exile target creature. Create a 2/2 white Spirit Soldier creature token.
-6: Transform Elspeth, Bound to Godsend and attach it to target creature you control.
/// Godsend, Essence of Elspeth
• Legendary Artifact - Equipment
Equipped creature gets +4/+4 and has flying, lifelink, and prowess.
Whenever equipped creature deals combat damage to a player, exile all creatures that player controls for as long as Godsend is attached to equipped creature. 4: Unattach Godsend, Essence of Elspeth, put a loyalty counter on it, and transform it. Activate this ability only any time you could cast a sorcery.
Zakamono of the Warlike Arts2GUR
Planeswalker - Zakamono
+2: Until end of turn, creatures you control and creatures that enter the battlefield under your control have sensei 2 and are Monks in addition to their other types. (Whenever one of those creatures enters or leaves the battlefield, another target creature gets +2/+2 until end of turn or up to two other target creatures get +1/+1 until end of turn.)
-2: Create a 2/2 blue and red Moonfolk Samurai creature token with flying and bushido 2.
-8: You get an emblem with "Creatures you control get +2/+0 and are Ninjas in addition to their other types. Creature cards in your hand have ninjutsu 3."
The idea being a Monk, Samurai, and Ninja mechanic.
Next: Someone from Theros, going through culture shock on Kaladesh.
Garth the Duelist3GU
Planeswalker - Garth
+1: Regenerate all permanents you control.
-3: The next time target player casts a spell, counter that spell.
-3: Create a 3/5 green Treefolk creature token named Ironroot Treefolk.
Next: Another planeswalker based on a pre-revisionist character. Alternately, Kiora working with Tamiyo.
Ulamog, Emrakul's Lich10
Legendary Creature - Eldrazi Zombie
You may put twenty cards your opponents own from exile into their owners' graveyards rather than pay Ulamog, Emrakul's Lich's mana cost.
When you cast Ulamog, Emrakul's Lich, target player loses 5 life and you gain 5 life.
At the beginning of your upkeep, exile target creature or land.
When Ulamog is put into a graveyard from anywhere, its owner shuffles his or her graveyard into his or her library. (Melds with Kozilek, Emrakul's Revenant.)
Kozilek, Emrakul's Revenant9CC
Legendary Creature - Eldrazi Spirit
When you cast Kozilek, Emrakul's Revenant, add CCCCC to your mana pool, then search your library for a nonlegendary card, reveal it, and put it into your hand. Shuffle your library afterwards.
Kozilek, Emrakul's Revenant can't be blocked by creatures with flying.
At the beginning of your upkeep, draw a card.
At the beginning of your end step, if you both own and control Kozilek, Emrakul's Revenant and a creature named Ulamog, Emrakul's Lich, exile them, then meld them into Gomkeliz, Death Knell of the Multiverse.
When Kozilek is put into a graveyard from anywhere, its owner shuffles his or her graveyard into his or her library.
Gomkeliz, Death Knell of the Multiverse
• Planeswalker - Gomkeliz
+2: Create two 3/2 colorless Eldrazi Horror creature tokens.
-10: Target player loses 13 life. Exile thirteen cards at random from that player's hand and the top thirteen cards of that player's library.
-24: The next time you start a game against target opponent, at the beginning of the first upkeep of that game, that player loses the game.
I sincerely hope you're happy.
Next: An Innistradi planeswalker on Zendikar, or vice-versa, who is nothing like this horrendous mess.
Gideon, Master of Discipline2WW
Planeswalker - Gideon
Creatures you control have "1, T: Put a +1/+1 counter on another target creature or a loyalty counter on target planeswalker."
Creatures you don't control have "Whenever this creature attacks, it doesn't untap during its controller's next untap step."
-3: Create a 2/2 white Knight creature token with vigilance. Gideon, Master of Discipline deals 3 damage to up to one target tapped creature.
Dovin, Living Shutdown1WU
Planeswalker - Dovin
+1: Up to one target creature gets +1/+3 and gains defender until your next turn.
-2: Until your next turn, activated abilities that aren't mana abilities can't be activated.
-6: Tap all permanents you don't control. Untap all permanents you control.
Next: A planeswalker whose persona is sort of like a pro wrestler.