Let's see what I can manage...
from an earlier thread of mine:
Hunters' Mystery Rite - 2G
Sorcery Formidable — When you cast Hunters' Mystery Rite, if creatures you control have total power 8 or greater, copy it for each creature you control. Each copy targets a different one of those creatures. Ferocious — If you control a creature with power 4 or greater, draw a card.
Untap target creature you control and put a +1/+1 counter on it.
Millennial Festival of (city) - 1W
Legendary Enchantment Constellation - Whenever Millennial Festival of (city) or another enchantment enters the battlefield under your control, gain 1 life and put a Festival counter on Millennial Festival of (city). If there are 5 or more Festival counters on Millennial Festival of (city), remove them and transform Millennial Festival of (city). Landfall - Whenever a land enters the battlefield under your control, gain 1 life and put a Festival counter on Millennial Festival of (city). If there are 5 or more Festival counters on Millennial Festival of (city), remove them and transform Millennial Festival of (city).
(name), Plaza of Commemoration
Legendary Enchantment Land (I really want this so I'm not budging here haha)
Creatures you control get +1/+1.
: Add one mana of any color.
I'm not sure what to do for Blue, but I decided the card would get Will of the Council and Addendum because it just seems right flavorfully.
Brainbarbs - B
Target player discards a non-land card. Delirium - If there are four or more card types among cards in your graveyard, instead that player reveals their hand, then you choose a non-land card from it, and that player discards that card. (may need better templating here.) Threshold - If seven or more cards are in your graveyard, that player loses life equal to that card's converted mana cost.
Unrelenting Slash-Slasher - 3RR (obviously I need a better card name)
Creature - Human Warrior
Haste Raid — When Unrelenting Slash-Slasher enters the battlefield, Relentless Assault. (help with the precise templating? I had something but I didn't like the way it read.) Battalion - Whenever Unrelenting Slash-Slasher and at least two other creatures attack, attacking creatures gain double strike until end of turn.
Using ability words rather than keyword mechanics results in extremely wordy cards.
Brainbarbs doesn't work as written. You can't have an opponent discard a specified card type without them revealing their hand. I guess hypothetically you could, but every time they claimed they only had lands in hand, a judge would probably be called over.
The red one is pretty overpowered. There is a reason that essentially no creatures create extra combats on etb. The double strike on battalion is worth 5 mana alone.