Ok, so let's pretend Kazumi has Partner with...

Kekomi, Flock's Redeemer

Legendary Creature - Moonfolk Cleric

Partner with Kazumi, Shepherd of Redemption

Ward

At the beginning of each combat, you may return a land you control to its owner's hand. If you do, create three 1/1 red spirit creature tokens with haste. Sacrifice them at the beginning of the next end step.

2/4

Create the enemy character to these two.

Sweve76: Thanks a lot for your upvote and comment. I see the problem, but Spidersilk Armor feels a little too specific for a card I can't tutor up. I've had Whiptongue Hydra in here for a while. Maybe I should put it back in. What do you think?

It actually seems kinda hard to combine each ability in a creature. Izzet has abilities for Instants/Sorceries. For simic, Graft and Evolve nonbo with Adapt. Bloodrush is a bummer as you need a way to recurr it to hand, which can't be done with Bloodthirst or Riot. Boros would work, but is incredibly boring with Battalion, Mentor and Radiance. Selesnya has only two keywords, as convoke is simply too perfect. Dimir is weird with surveil being evergreen and Transmute being another discard.

You know what? I'll do Rakdos :D

Rakdos, Entity of Slaughter

Legendary Creature - Demon

Flying, Trample, Unleash

Hellbent - As long as you have no cards in hand, this spell costs less to cast.

Spectacle

6/6

Repeat if you want to. Otherwise wild.

Fjodor, Frostburn Invoker

Legendary Creature - Human Warlock

Whenever a spell or ability you control causes a creature to become tapped, you may discard a card. If you do, create a 2/2 blue and black elemental creature token.

: Tap target creature, then put a +1/+1 counter on target creature token you control.

3/3

Create a rakdos enchantress.

Tamait, Foil to the Godess

Legendary Creature - Dragon God

Flying

Undying, Vigilance, Pestilence 4

While you’re searching your library, you may cast dragon spells from your library.

6/6

A single dragon couldn't match her that easily. But what if he just had the help of all the dragons?

Create a legendary wurm in Bant colours.

Spirit Realm Expansion

Sorcery - Arcane

A deck may contain any number of cards named ~.

Scry 1, then draw a card.

Splice onto Arcane

Create a legendary spirit that would want to play this in its commander deck.

Serra, the Sculptor

Legendary Planeswalker - Serra

Whenever an angel you control enters, put an amount of loyalty counters on Serra equal to its toughness.

+1 Create a 4/4 white angel creature token with flying and vigilance.

-4 Exile target creature. Its controller gains life equal to its power.

-20: Exile all nonland permanents you don't control.

3

Create a snow elemental.

Benjen, Beamtown Juggernaut

Legendary Planeswalker - Benjen

Rhinos you control get +2/+2 and gain vigilance and trample.

+1 Destroy target noncreature permanent. Its controller creates a 3/3 green rhino creature token.

-3 Reveal cards from the top of your library until you reveal a rhino creature card. Put that card onto the battlefield, then shuffle the rest into your library. When a creature enters this way, it gains "When this creature enters, it fights up to one target creature you don't control."

5

Benjen, Beamtown Juggernaut can be your commander.

Create a mythic rare sloth creature.

Crow_Umbra: Ah crap, I meant to write nontoken artifact, so you couldn't just blow up your own food tokens for lands.

Timbles, Obsessive Nibbler

Legendary Creature - Beaver Berserker

Islandwalk

Whenever this creature enters or attacks, destroy target nonartifact artifact or enchantment. Its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffles.

On Bloomburrow, Timbles wrecked some havoc. On Kamigawa, he could hardly not wreck all of it.

3/4

Repeat.

Duskwalker Sentinel

Artifact Creature - Gargoyle

Flying, Defender

Whenever this creature or another gargoyle you control enters, gargoyle creatures you control may attack as though they didn't have have defender.

4/5

This sat quite a while. If you want to, continue with simic. Otherwise, just do wild.

You might be interested in Tarrian's Soulcleaver. You mentioned giving Mag vigilance before wiping during an attack. Cleaver is the perfect weapon for that.