I'm currently collecting how people in the cube community feel about Theros Beyond Death, and I would be remiss to miss out on MTGSalvation as a place to gather data! I did the same thing for Throne of Eldraine, and you can see the results of that data collection here - Throne of Eldraine Community Testing. Many of the members of the community here participated!
Cube lists of all shapes and sizes are welcome! You can either fill out this survey or post your testing list below, along with card rankings. For card rankings, a rank of 1 means that you think the card is unlikely to make it through testing or you're unexcited about testing it. A rank of 2 means that you're medium on the card, but you think it has a decent shot of making it through testing. A rank of 3 means that the card is a windmill slam inclusion in your list. Feel free to use fractional rankings (ie 2.5).