This is a budget cube, including modified cards.

Rules Changes:
All games begin with a copy of Damping Sphere, and Void Mirror on the battlefield.

Furthermore, this cube contains no "hard counters" with 1 exception for the iconic Counterspell itself. This is in the hopes of weakening Blue Aggro decks, which typically have a very strong late-game due to fliers.

This cube contains a number of modified cards (too many to list), and creates a couple of cycles by modifying mana costs.

One such cycle is the 2 cmc "One word, simple effect" cycle:
Counterspell - Counter target spell.
Resurrection - Return target creature to play.
Murder - Destroy target creature. (also Damn)
Harmonize - Draw three cards.
Pillage - Destroy target artifact or land.

The cube includes a number of self-referential cards. With the exception of Rekindling Phoenix, when you draft these cards you receive a playset of them at the end of drafting. With Seven Dwarves, this means you get 6. This is to make it possible to safely to draft mono or dual colored decks, in a cube that I flooded with gold cards.

The cube pays attention to the color pie, with:
White focused on Peace and Cats
Blue focused on Intellect and Wizards
Black focused on Ambition and Graveyards
Red focused on Impulsiveness and Chaos
Green focused on Nature and Growth

Combos
Red has pump cards and a number of creatures with Double Strike, which will double the benefit of the pump cards.
Blue has wizard synergies.
White has
Black has
Green has