Adjustments

Tireless Tracker. Landfall isn't really all that great if tracker doesn't come down on turn three. Late game it's a pretty bad card as just a 3 mana 3/2. I made this change in paper before I decided what card should replace this. At the time I went with Runic Armasaur which has been a pretty good fit. It blocks really well and is great at pulling value out of what the opponent is doing.

Student of warfare doesn't quite feel good. Contributing resources to the board is more necessary than trying to get damage in early. Committing mana to student is almost always worse than just playing a card from your hand.

Ashiok, Nightmare Weaver is very slow. While it's possible for it to take over the game, it doesn't feel nice to play with. Hostage Taker is much more interactive and contributes better to the kind of games I want to promote.

More multicolored cards

I want to expand out the multicolored section a bit. Add some more diversity in the cards players can see and dilute some of the single colored cards that are really easy to cast.

Baleful Strix is a card that can buy you some time to gather resources or get out of a bad situation. It feels like a great card to try out.

Soulherder is the kind of card that I could see adjusting other slots in the cube to accommodate. It has some synergies with other cards: Blade Splicer, Thragtusk, Esika's Chariot. If those aren't enough I'll likely swap this card for something else or add add a few more value targets.

Falkenrath Aristocrat. There are a lot of ways to make tokens in the cube, what if we gave those a second use?

Gallia of the Endless Dance is pretty good on it's own, while also synergizing with Xenagos, the Reveler. This could be really fun or a dud, we'll find out with testing.

Dromoka's Command does a lot of the stuff missing in this cube. It counters some removal, kills enchantments, and is a pretty good combat trick.

Dire Tactics. Conditional removal with a conditional downside. This kills a number of cards in the cube that are otherwise hard to get rid of. This card may be good enough, in conjunction with other tweaks, to kick Swords out of it's slot in the cube.

The Royal Scions. Blue/Red really stumped me. I'm not sure what the cube needs that this color pair can easily provide. There are plenty of big creatures and spells matters cards, but I don't know that I want either of those. The Royal Scions are pretty good at digging for a card you want and giving an extra push to get in for damage. If this card doesn't work out I'll try out Ludevic, Necro-Alchemist.

Find // Finality seems like a pretty decent card for the cube over all. Boardwipes are appreciated since the boards can clog. It also plays really well with Pack Rat and Liliana, Death's Majesty.

Aurelia, the Warleader is just a chonker like Koma, Cosmos Serpent and Beledros Witherbloom. At four color pips she rewards the player for watching their fixing carefully. She's not as powerful as Koma, but hopefully closes out games quick enough for that not to matter. Out of all the big boros creatures I chose her for the color pips and because she dies to a bit more removal than Gisela, Blade of Goldnight and Velomachus Lorehold that were also considered.

Cold-Eyed Selkie has a landwalk ability and a relevant ability that triggers from it. I want to experiment with landwalk since it can change how the opponent picks the lands they play each turn. The selkie gets worse when the opponent doesn't grab an island, but do they want to forgo being able to cast a card in the queue or their hand?