You can check out the cards in the Dominaria United Commander Card Image Gallery, as well as the regular cards in the Dominaria United Card Image Gallery and the Booster Fun variants of Dominaria United cards
They then split up the possible inclusions into three tiers - what Verhey described as the "gotta have: primary elements and most popular characters, followed by the second tier, which is where cool side characters came into play, while the third tier were the deep cuts, like Guy speaking beaver
This makes all your opponents go through the villainous choice regardless of in-game actions , and it triggers for each opponent, so you can be drawing three cards or dealing a lot of burn damage with your Cybermen
It can be a card neutral chump for slower decks or a free beater with some utility for aggro decks
There is a minor blue/black Proliferate/sacrifice archetype, which uses artifacts ranging from Throne of Geth to Lux Cannon (Proliferate works on charge counters as well as +1/+1 counters)
Knuckleblade has so many abilities that there isnt even room for flavor text