Commander: 99 card deck + a Commander card.
There is no unified construction, though each player's deck should be a legal Commander deck by itself.
Each deck must fall with bracket 3
Each team starts with 60 life.

No Infinite combos

A team loses when they take 21 or more damage from a single commander OR have 15 or more poison counters.

What is Bracket 3?

Bracket 3: Upgraded
Experience: These decks are souped up and ready to play beyond the strength of an average preconstructed deck.
They are full of carefully selected cards, with work having gone into figuring out the best card for each slot. The games tend to be a little faster as well, ending a turn or two sooner than your Core (Bracket 2) decks. This also is where players can begin playing up to three cards from the Game Changers list, amping up the decks further. Of course, it doesn't have to have any Game Changers to be a Bracket 3 deck: many decks are more powerful than a preconstructed deck, even without them!
These decks should generally not have any two-card infinite combos that can happen cheaply and in about the first six or so turns of the game, but it's possible the long game could end with one being deployed, even out of nowhere.
Deck Building: Up to three cards from the Game Changers list. No intentional early-game two-card infinite combos. Extra-turn cards should only appear in low quantities and are not intended to be chained in succession or looped. No mass land denial.