A 4/4 Vigilance for four mana is at least playable… sort of. And there’s quite a few knights available. I thought they were supposed to be rarer than soldiers?

Aryel, Knight of Windgrace
2WB
Legendary Creature – Human Knight
Vigilance

2W, T: Create a 2/2 white Knight creature token with vigilance.

B, T, Tap X untapped Knights you control: Destroy target creature with power X or less.
4/4

Of course, it’s an engine on it’s own, with no need for help, but I’ll try to help her out anyhow.

There are 15 black and white knights in the Ixalan block. Some of them have dinosaur synergies and some are just not up to the standars, so we can’t play them all. Kaladesh and Amonkhet have no knights in them. Let’s start with these:

Not too many. Dominaria has more. We have [scryfall]Knight of Grace[/scryfall] and it’s counterpart [scryfall]Knight of Malice[/scryfall]. [scryfall]Dauntless Bodyguard[/scryfall] is definitely useful. [scryfall]Arvad the Cursed[/scryfall] even happens to be vampire as well, which can be helpful. [scryfall]History of Benalia[/scryfall] gives us two knights and pumps the existing ones.

That’s only 13 cards, so we have to work a bit to fill the holes. I want to put [scryfall]The Eldest Reborn[/scryfall] into the deck. Seems like a fine addition. [scryfall]Baird, Steward of Argive[/scryfall] is good protection in a multiplayer format. Next, a bunch of removal. Gladly, this is what these two colors do well.

Of course, some card draw / selection would be nice as well.

That’s 34 cards with one land. Now, since I have places to put my mana here, I wouldn’t mind 26 lands, which leaves room for only one more spell. I’m not sure what it should be, so I’ll throw in [scryfall]Kambal, Consul of Allocation[/scryfall].

[deck]
[commander]
Aryel, Knight of Windgrace
[/commander]
[creatures]
Bloodcrazed Paladin
Champion of Dusk
Elenda, the Dusk Rose
Oathsworn Vampire
Paladin of Atonement
Sanctum Seeker
Vona, Butcher of Magan
Metallic Mimic
Knight of Grace
Knight of Malice
Dauntless Bodyguard
Arvad the Cursed
Baird, Steward of Argive
Angel of Sanctions
Noxious Gearhulk
Ravenous Chupacabra
Tetzimoc, Primal Death
Kambal, Consul of Allocation
[/creatures]
[spells]
The Eldest Reborn
History of Benalia
Cast Out
Settle the Wreckage
Golden Demise
Walk the Plank
Dusk // Dawn
Grind // Dust
Hour of Revelation
Never // Return
Profane Procession
Skywhaler’s Shot
Arguel’s Blood Fast
Hidden Stockpile
Treasure Map
Sunset Pyramid
[/spells]
[lands]
Arch of Orazca
Isolated Chapel
Aether Hub
Concealed Courtyard
Evolving Wilds
Desert of the Glorified
Desert of the True
Field of Ruin
Forsaken Sanctuary
[/lands]
[/deck]