OK, then. My challenge still stands.

It's like Mileva on a bunch of Boros cards. Just make Catrina a Legendary Creature.

Bruna, Alabaster's Glow

Legendary Creature - Angel Spirit

Flying, Lifelink.

Whenever a creature dies or is put into a graveyard from anywhere, exile it instead.

Whenever a Creature in a graveyard becomes the target of a spell or ability, scry 3 and gain 5 life.

Partners with Gisela, Soul of the Goldnight.

Upon death, the two souls unmerged. No longer the beings they were, the two sisters sought to serve Innistrad in whatever way they could.

2/4

And Gisela, why not?

Gisela, Soul of the Goldnight

Legendary Creature - Angel Spirit

Flying, First Strike.

Attacking Creatures you control get +2/+1.

Whenever at least 4 creatures you control attack the same Opponent, create a tapped 1/3 White Angel Soldier Creature token with Flying that is attacking that Opponent. The token gains trample until the end of the turn.

Partners with Bruna, Alabaster's Glow.

At last free from Emrakul's control, Gisela and Bruna went back to doing what they knew best, even if they no longer had physical forms.

3/2

The flavor text on Order of the Mirror  ^Flip mentions a character named "Catrina." Make a Legendary Creature Card for Catrina (after her Phyrexian compleation).

Aslan, the Wise

Legendary Creature - Cat God

Vigilance, Lifelink.

Whenever a Human enters the battlefield, gain 2 life and scry 1.

5/4

Narnia is awesome! Now make a singular creature card that represents all 4 Pevensie kids while they were Kings and Queens of Narnia.

Leyline of Serenity

Enchantment

If Leyline of Serenity is in your opening hand, you may begin the game with it on the battlefield.

Whenever a Leyline Permanent enters the battlefield, gain life equal to its mana value. If you gained 7 or more life this way, scry 2 (Leyline permanents are enchantments, angels, elementals, oozes, spirits, and demons).

Of course I had to make a literal Leyline for the leylne permanents.

OK, so Demigod of Revenge functionally does not work for Commander. It's also the reason the entire cycle is NON-legendary, so make a new card that is still this thing, and still conveys the lore and gameplay ideas of this thing (go check out The Seer's Parable, if you need a refresh), but is a Legendary Creature.

Aura of Leadership

Enchantment - Aura

Enchant Creature.

Enchanted creature has +2/+2, First Strike, and Mentor.

Radiance - Whenever ~ leaves the battlefield, all creatures that shared a colour with the enchanted creature deal 1 damage to any target.

Aura Swap

Fortheboys11's original challenge was skipped. Go to their post with Esper Legalist, look at the creature, and then do their challenge. I'm curious to see what happens.

Trekkjin, Throne's Heir

Legendary Creature - Dragon

When ~ enters the battlefield, target opponent becomes the Monarch. That player can not attack you or Planeswalkers you control during their next turn.

Whenever you become the Monarch, untap ~.

: Add . Activate this ability only if you are the Monarch.

Partners with Grinslin, Trusted Advisor.

1/3

Grinslin, Trusted Advisor

Legendary Creature - Human Advisor

Whenever a player becomes the Monarch, scry 2.

Whenever you activate a mana ability, if you are the Monarch, instead add that much mana of any colour.

Partners with Trekkjin, Throne's Heir.

0/5

Remember Arcanum Wings? Make another Aura with Aura Swap.

Insurgent

Creature - Citizen Soldier

Disguise

Shroud.

As long as you are not the Monarch, ~ gets +3/+2. Whenever ~ attacks the Monarch, it gains Trample until the end of the turn.

3/3

Wild.

Wand of the King

Artifact - Equipment

Equipped creature gets -1/+0. If you are not the Monarch, equipped creature has protection from the Monarch and from creatures the Monarch controls.

If Wand of the King is equipped, Instants, Sorceries and Enchantments cost less to cast. If you are the Monarch, they instead cost less to cast, where X is equipped creature's power.

Equip

I believe that White should have the most support for the Monarch mechanic. Make another white artifact that has an effect that gets more powerful if you are the Monarch. Bonus points if the artifact itself does NOT make you the Monarch.