Bracket Level 1 - Random Chance: How to do it.

Step 1 - Go to scryfall and hit random until you get a commander. That is your commander. Step 2 - Add basic lands that equal 30 for the commanders colour, if you got a colorless random commander add 30 wastes. Step 3 - Back to scryfall and hit random, every card it shows that fits your commanders colours and is legal goes in your deck until you reach 100 cards.

Note: A user by the name RagingAcid has made Step 3 a little easier by using the following search query on Scryfall. Simply go to this link, change the colour id to your random commander (this example is using Green/White). Randomise away

https://scryfall.com/random?q=id:gw

All Done.