Democratic Process

Sorcery

Each player may create a Veto token with "Pay : Sacrifice this artifact: Counter target non creature spell. That spell's controller draws two cards." For each player who does, create a treasure token.

"The process must allow for everyone's voice to be heard. This way there are no qualms when the result is purchased."

Did my own challenge cause I always feel bad when a prompt goes unanswered for two or more days. Repeat or Wild

capwner supposed to be the latter yea, missed that in edits.

Perchance to Dream

Enchantment

At the beginning of each upkeep each player chooses Slumber or Sustenance.

Sleep - You cannot cast spells this turn. At the beginning of your next upkeep, draw two cards. Create a Moonlit Path enchantment token with "Sacrifice: Add three mana of any one color to your mana pool."

Sustenance - Create your choice of a tapped treasure or food token. The first spell you cast this turn costs less to cast.

"Many mages think they can create some ultimate spell to craft everything to their whim. The truth in power lies in choice, and the more choice you allow an opponent the more deadly a spell can be."

Create a card like the one above which forces players to play the game a bit differently. Bonus points if choice is involved

(And repeat challenge OR make a card that somehow benefits from "once a turn" effects)

Throw the Brick

Instant

Destroy target artifact or nonbasic land. When this is cast, if it’s your main phase, there is an additional combat phase after this phase followed by an additional main phase. When you next attack this turn, untap each creature you control.

"“We are the Stonewall girls/ We wear our hair in curls/ We wear no underwear/ We show our pubic hair…/ We wear our dungarees/ Above our Nelly knees!"