Ravnica is by far my favorite Magic: The Gathering setting. This cube is meant to provide a nostalgic trip down the streets of the plane of Ravnica, while simultaneously giving a cube experience. I've included a lot of the classic Ravnica cards to bring out the themes and feeling of the city plane and the guilds that inhabit it. There is a hand picked guildmage for each guild. There is a cycle of the guild utility lands (though I have included a Ral Planeswalker instead of Nivix, Aerie of the Firemind, because the Izzet deck needed the support, and Nivix sucks). There are even War of the Spark cards that exude flavor or highlight specific characters of the world. Each guild is represented with a specific theme/archetype and there are potential crossover synergies between them. I have also tried to include seeds of additional interesting archetypes and deck synergies to see what other strategies might develop as the cube gets played. The main archetypes I have tried to support are as follows.

Boros: Beatdown aggro w. Battalion themes

Rakdos: Hellbent Aggro & some Sacrifice

Izzet: Spells Matter: Instant & Sorcery synergies

Gruul: Ramping & large creatures. Focus on a Creature only deck w. Nikya of the old ways. Mana sinks on your creatures for value in the late game.

Dimir: Mill & Control

Simic: +1/+1 Counters

Azorius: Control & Flier Tempo (skies)

Golgari: Graveyard Value (Dredge, Scavenge, Sacrifice, Reanimation)

Selsnya: Tokens, Token Synergies & Go Wide

Orzhov: Sacrifice & Value Grind

I have also tried to support a few other archetypes. There is support for a 5 color good stuff deck (probably base green) with the inclusion of a lot of Mana fixing (two of each Guildgate, Shock Lands, Signets, Keyrunes & cluestones) This deck may be hard to get to come together, but when it does it will have very powerful cards and Niv Mizzet Reborn will draw lots of them.

There is also a Grixis tempo deck which uses Dimir Cutpurse, Thief of Sanity, Stealer of Secrets, Nightveil Specter, & Krenko, Tin Street Kingpin along with the cheap red & black removal to clear the way for them early and out tempo the opponent. This archetype might benefit from some Cipher cards, but none are included as of yet. There are also some seeds for a Mardu Life gain deck built around searing meditation, Karlov of the Ghost Council and some of the repeatable life gain effects in white & black. This deck would likely also be difficult to get to come together, but probably a lot of fun if you do manage it. lastly, there is a Cloudstone Curio in the cube which allows for some interesting shenanigans. I'm not sure just how well supported this would be as a build around, but at the cost of 1 card slot in the cube, it seemed worth trying to see if a fun deck can coalesce around it. If it isn't quite there, more ETB effects creatures can be added to make it work. There is also good seeds for a reanimator deck with some choice targets like Blazing Archon, Tidespout Tyrant, & Lord of the Void. It might be a little tricky to get them in the graveyard, but definitely possible. other potential build arounds include Debotors knell, Illusionist Bracers, Muse Vessel, Alhameret's Archive, Mizzix's Mastery, Experimental Frenzy, Rakdos Riteknife, Blind Obedience, Rakdos Augermage, & Nhilisitc Glee. Testing will show whether these cards deserve a slot in the cube or not.