For my 1vs 1 cube, on first pass
Includes
I've found that Green lacks some good GY payoffs, and the monkey does a good job at it, in addition to counters and artifact synergies. It lacks trample to be really good, but it still seems worth it.
Double Strike is a very powerful keyword in cubes where +1/+1 counters are present. 3 mana 2/2 is rough, but when you factor in the recursion late game or synergy potential with Welder, it gets interesting!
Fleshgorger's main mode will probably be as a cheat target, but having the backup of a 3/3 for 3 with relevant types, keywords and protection is great. I am looking at other prototype cards, but this is the main one.
Iconoclast is the perfect glue card. It's cheap, has a relevant body, triggers off of noncreature spells and makes artifacts. The body + mana cost makes it a slam dunk for me whereas
Saheeli, Sublime Artificer failed. In slower environments, I think having both would be great!
Tests
Unearth plays really well and this more versatile version seems worth it at 2 mana. Getting back the aforementioned Dragon Engine with a +1/+1 counter and the 3 cards seems like a great play sequence to give aggro decks late game potential. I'm 90% sure this will stick.
Officer also plays with the late game value plan. Not exciting, but good for gameplay.
The Assembler, Seraph, Thresher and Amalgam hit the relevant early and late notes. They have synergy with blink and the first 2 with counters. Finding space is tough though, especially for the 3 drop prototypes. I am leaning towards the 2 drops because my 3s are already jam packed!
Teferi's ceiling is awfully high, as chaining it with any kind of
Wheel effect is bonkers. It's also decent on it's own and together with the new
Sheoldred, might make for a cool subtheme in Grixis. The floor on the card is certainly disappointing, but not a deal breaker IMO.
Thopter Mechanic works well in a lot of archetypes. Spell velocity, humans, counters, sacrifice and artifacts all could care about it. It's not very exciting, but might just be versatile enough to warrant a slot.
The Desk is a cool Bauble type card. I'll have to do the math on whether or not I need an instant/sorcery more than an artifact for my archetypes.
Not sure I need
Satyr Wayfinder #2, but definitely a contender.
I often end up drafting a human/artifact/counter deck with White in it, so the Dissident is appealing. Might not be impactful enough as a 1/1 for my power level though.
Cosmetic upgrades
This is the part that has me the most excited. Between the old bordered artifacts and the retro frame commander products, there are going to be a lot of "upgrades"!