This cube is build upon all 3 Ravnica cubes, excluding "War of the Spark" planeswalker specific cards.

The template I build for this cube is as follows:

150 Guild cards

• 10x 15 Two-Color cards per guild

290 Mono-Color cards

• 5x 58 Mono-Color cards per color including
  -- 4x 12 guild-themed Mono-Color cards per aligned guild
  -- 10 non-guild-themed Mono-color cards

25 colorless cards

• 10 Signets
• 10 Lockets
• 5 other artifacts

75 Land cards

• 70x Guild Lands including
  -- 3 Gates per guild
  -- 2 Shock-Lands per guild
  -- 1 Bounce-Land per guild
  -- 1 Theme Land per guild
• 5x Multi-Color Lands

So every guild theme is supported by 15 2-color cards and 2x12 guild-themed mono-color cards. Additionally each guild benefits from synergies between guilds, so going 3-color during draft is a more than viable choice.

I will be seeding the 36 Boosters with at least 2 lands per pack.