Thrummingbird:
Various counters have been streaming into the cube over the past few years, that Thrummingbird can find its nest here in the main list.

Blazing Crescendo replaces Fists of Flame:
This matchup is dependent on where these cards go. Blazing Crescendo works harmoniously in aggressive and mid-range strategies, as it doesn't require the build up that Fists of Flame does to punch over the top of blockers and close out the game. Fists of Flame works best in spell-fist strategies that can ball up a grip of extra mana and card draw. If we're looking at the draw effect on the card, then impulse effects are effectively card draw in decks that do care about the front part of the effect.

Bladegraft Aspirant & Barbed Batterfist:
Bladegraft Aspirant is equipped with an arsenal of abilities that would put this card at the same power level of as an uncommon. This card inserts itself in the same decks as the reconfigurable equipment creatures from Kamigawa:Neon Dynasty. Batterfist packs a punch for just two mana!

Contagious Vorrac replaces Spore Crawler:
It's so hard not to pig out on all the card draw. Contagious Vorrac will draw you a land (still a card) and has the added flexibility of proliferating. In a dedicated counters deck this effect can be worth more than a card.

Planar Disruption replaces Faith's Fetters:
This card does a better job at disrupting your opponent's plans as it comes down couple of turns quicker. We will see if trading off life gain for speed and cost efficiency is worth it. It is worth noting that Battles a new type of card could be hit by Faith's Fetters in future updates.

Vanish into Eternity:
Fits same role as Angelic purge. More expensive as creature removal, however not having to sac and hitting more permanent types may be relevant in the future (with battles on the horizon).

Experimental Augury replaces Curate:
Curate is tailored to an environment that cares about fueling your graveyard whereas Experimental Augury is more at home in this update. The one upside is that Experimental Augury looks at an extra card more for selection. With the number of playable spells in the cube, it is no hard task to fill up the graveyard.

Indoctrination Attendant:
Not quite the Icewind Stalwart, this creature does assist the flicker or buy-back decks replay cards for value.

Blightbelly Rat:
I hope you haven't had your fill of toxic decks. Blightbelly Rat serves as both an enabler for poisoning your opponent out and a proliferater for all the counter matter shenanigans.

The Gates replace the Snow Dual lands
(Basilisk Gate, Heap Gate, & .... Azorius Gate replaces Snowfield Sinkhole, & .... Glacial Floodplain):
This land cycle was initially in the honourable mention section during the Commander Legends: Baldur's Gate update. It turns out having a repeatable pump effect on your lands is a really good way to make use of your flooding. As the recent CawGate deck performances have shown, just having two more gates and a Basilik Gate can turn any of your dorky 1/1 recurring creatures into serious threats. While not in the same decks, the treasures generated by Heap Gate offer a wealth of synergies with the sacrifice decks. The snow duals are being put on ice until more incidental domain or land type synergies emerge.

The Sphere land cycle
(The Fair Basilica, The Surgical Bay, The Dross Pits, The Autonomous Furnace, & The Hunter Maze):
Being able to cycle these later in the game is amazing. There's just not enough to get the ball rolling on adding these into the cube.

The Depletion land cycle
(Remote Farm, Saprazzan Skerry, Peat Bog, Sandstone Needle, & Hickory Woodlot):
These would be a snap inclusion in this update if it weren't for the fact that these lands would deplete my funds. Optional inclusions for any cubers wanting to build this update.

Annihilating Glare:
If you look closely enough this is much like the other Bone Splinter variants in the cube, with the added benefit of being able to sacrifice artifacts too.

Prologue to Phyresis:
This is such a unique effect. Unfortunately there isn't much in the way of applying accidental poison to your opponent. With enough poison counters this could be the beginning of a new archetype.