Hello everybody! Not english-speaker here, so be kind please. This post is a follow up from there.

I need HELP for the balance revision of the cards i have done so far. If you like mtg and Nintendo as much as i do, being able to read and comment a big batch of cards will be fun for sure.

I want to preface that this is the first shard i completed (only the mono-colored cards are provided), but rarities and numbers are still pending. Also, a little bit about how i tackled the problem about the cube design: read the following if you want, but there will be a big list of cards down on the post.

Mario Cube Design

I follow this points while designing the set.

1. Cube design. Instead of jumping in and designing single cards, i started by defining the number of cards for each single shard. Since the number of unique card in the cube is 360, i assigned 60 cards for each shard, 30 nonbasic lands and 30 colorless artifacts. I want the cube to feel like a set, therefore i will draft with three copies of each common, two of each uncommon and one of each "rare" (rares and mythics combined) and then pick the packs for the 360-card draft from a total of 780 cards (160 unique commons, 120 unique uncommons and 80 unique rares).
2. Shard design. Since Shards are based around a primary color and two allied colors, i wanted the number of cards on the shard to reflect that (30 cards of the primary color, 10 cards of the allied colors and 10 multicolored cards will be a suitable split). Rarities will be split equally in between the shards, but this is a process i will do by brute force with excel down the line... for now i'm doing it by intuition. There are data online about a good split between creatures and spells in any given color and mana curves, so i made mine using other people built one.
3. Archetype design. Usually, the art of creating a cube is associated to picking cards that subtly can work in different archetypes (favoring cards that are used in multiple archetypes instead of straightforward ones) and balancing the choices through gameplay. Since we are designing cards from scratch, i choose to modify pre-existing alpha cards on a second stage of the design to implement subtly more archetypes on the cube. Right now, they should be mostly focused on the core shard theme, this is done by purpose.
4. Cards design. This point is the one i need help the most. As a starting point, i want to preface that the most important points for designing cards are (for me) in order Art, Elegance, Flavor/Function.

• Art: Artworks can be the best and the worst thing about a magic card. I scoured the web to find usable images (for my tastes) and after that design the cards. I was in trouble whenever i tried to design cycles, before it was always super hard to find the right art piece for the last card... so i decided to put the art as the first most important point. Once the art was good enough, the card could have been designed (but still there are many i don't like much). Everyone is welcome to use the artwork i found, as long as the original artist is referenced in your card.
• Elegance: I like simple cards. Long and convoluted effects are bad to look at and play with. Whenever characters have many different abilities i tried to split them in different cards (e.g. Yoshi is able to be a mount, fly, lay eggs... so i wrote a yoshi creature and a spell to throw and create eggs, for example).
• Flavor/Function: Effects of the cards must represent what they are (and there are infinite ways to write down a Mario card) and be playable in the set they belong. Flavor and function are linked, in my opinion, and must be considered together. Everyone is welcome to use the cards i designed, as long as i am referenced somewhere in the card.

Jund Shard (bRg) - Koopa Troop Alpha

The primary color of the shard is red, while green and black are secondary colors. The keyword is Spawn, that i rewrote sligthly as:

Spawn
Spawn X - [cost] ([cost], Exile this card from your hand: Create X 1/1 Minion creature tokens of the same color of the exiled card. You may cast this card later from exile. Spawn only as a sorcery.)

The followings are the cards in the shard.

• 30 red cards (55% [17] creatures, 45% [13] spells) (Koopa troop)
• 0 CMC: 1

Shy Guy creature

• 1 CMC: 5

Lava Bubble creature

Red Shell spell

Bob-omb creature

Spiny Walker creature

Bullet Bill spell

• 2 CMC: 8

Fire Bro, creature

Sergeant Guy creature

Goomba Tower creature

Mouser, creature

Setting the Stage, spell

King Bill, spell

Assessing Danger, spell

Lava Level spell

• 3 CMC: 10

Chargin' Chuck creature

Goomboss creature

Big Bob-omb creature

Koopatrol, creature

Jr. Troopa creature

Join the Troop, spell

Rally the Troopas, spell

Bullet Hell, spell

Koopa's Treasure, spell - part of a cycle

King Koopa's Monument, spell - part of a cycle

• 4 CMC: 2

Koopalings creature

Overwhelming Invasion , spell

• 5 CMC: 2

Bowser Jr. creature

Royal Flamebreath, spell

• 6 CMC: 1

Bowser, King Koopa, creature (Giga Bowser extra in Jund)

• 7 CMC: 0
• 8 CMC: 1

Ruined Dragon creature

• 10 black cards (55% [6] creatures, 45% [4] spells)
  • 0 CMC: 0
  • 1 CMC: 1

Toady Underling, creature

• 2 CMC: 4

Dry Bones, creature

Memoir's Perusal, spell

Lakitu Bomber, creature

Extreme Measures, spell

• 3 CMC: 3

Skeleton Outbreak, spell

Giga Lakitu creature

Magikoopa creature

• 4 CMC: 1

Preventive Snatch spell

• 5 CMC: 1

Kamek, Arch-Magikoopa creature

• 10 green cards (70% [7] creatures, 30% [3] spells)
• token:

Piranha Plant

• 0 CMC: 0
• 1 CMC: 2

Koopa Henchman, creature

Muncher , creature

• 2 CMC: 3

Spear Guy, creature

Piranha Plant, creature

Rex, creature

• 3 CMC: 3

Tribal Ritual, spell

Dino Invasion, spell

Hammer Bro, creature

• 4 CMC: 2

Jungle Hunt, spell

Wart, creature

• 6 CMC: 1

Megasmilax Sprout, spell

Revision and Conclusion

If you want to help me, i have the following questions to answer:

1. What's the card you think is the least flavorful? Why?
2. What common red effects/cards are missing from the set? (Notice that artifact destruction and impulsive draw are in other shards)
3. What cards are busted and why? If you can, add other mtg real cards with similar cost/effect for reference.
4. Have you got other interesting 2d artworks that can be used? (Especially for Fire Bro, Red Shell and Shy Guy...)

Thank you very much for your attention!