172 Commons
64 Uncommons
28 Rares
6 Mythicals

Based on the following tier list for balancing:
https://mtgazone.com/phyrexia-all-will-be-one-limited-tier-list/

Balancing spreadsheet:
https://docs.google.com/spreadsheets/d/10bY_XjlY2JIwwVFlbOIifTH0_Km61RwY_buoaTC_-pQ/edit#gid=1230282755

Common Rating Range: Min: 1.5 / Max: 3.0
Uncommon Rating Range: Min 2.0 / Max: 3.5
Rare Rating Range: Min 2.5 / Max: 4.0
Mythic Rating Range: Min 3.0 / Max: 4.5

Trying to have 2 copies of commons and 1 copy of other rarities. But sometimes extra duplicates are added for balancing purposes.

Exceptions for balancing purposes:

White (lack of options) - 1x Infested Fleshcutter - 1.5
White (lack of options) - 1x Annex Sentry - 4.0
Blue (add one high mana cost) - Watchfull Bliterzoa - 1.5
Green (weak commons in general) - 2x Contagious Vorrac - 3.5

Note: Not adding very expensive cards to this list except for Eleth Norn and Venerated Rotpriest which I already have. Can be replaced with Phyrexian Vindicator and a duplicate of one of the other green rares.

Note: This cube has extra rares and mythicals for variety. That means that it is designed to be Seeded.