Adding some older Werewolves in an attempt to buff the archetype. My impression while playing a Gruul deck during our last draft was that the board quickly stalls due to a lack of fast answers or ways to break through.
The Werewolves should be able to overwhelm the opponent if built aggressively.

Note that all Werewolves from older sets will have their flip rules replaced by the Daybound/Nightbound mechanic in this cube.

These additions were suggested by a friend after our most recent draft of the cube.

Selfless Spirit, Spell Queller, Niblis of Frost: Buffing Azorius Spirits. Selfless Spirit also protects against various board wipes.

Ishkanah, Grafwidow, Grim Flayer: Buffing Golgari, also adding some reach to green.

Spirit of the Hunt: Buffing Gruul Werewolves.

Collective Defiance: Adding a stronger red sorcery, particularly good for Izzet Spells.

Removed Cards

Ambitious Farmhand, Candlelit Cavalry: There were too many Humans in this cube, these are among the weaker.

Teferi, Who Slows the Sunset: Didn't really have anything to do with the Azorious archetype of Spirits and Enchantments.

Spore Crawler: The weakest green 3-drop.

Old Stickfingers: I've been told this before, but after drafting him myself I am forced to agree - this ability just doesn't work in a limited format. Grim Flayer supports the same archetype, but better.

Gutter Skulker: One of the weaker spirits in blue.

Ancient Grudge: After recently removing several artifacts, this became even weaker than it already was. There are much better red spells available for Izzet etc.

These cards are functionally identical in this cube, and I already had a Flame-Blessed Bolt.

I don't quite remember why I thought Hiveheart Shaman would fit in this cube. Maybe the slightly-above-average-toughness?
Anyway, Spider Spawning provides some additional graveyard / self-mill payoff.