Bonus Ball is a nice introduction to the concept of Recommission. A number of permanents will offer players the option to return them to hand and gain mana. The flavor of it is that you're, well, recommissioning robots and devices to gain access to their parts/energy, so they can be used for other, more advanced robots and devices.
Couple of commons, nothing too exciting here. But each mechanic has to spread across all rarities, so as to have a worthwhile impact on the set. See exalted in M13.
In Mega Man, the Screw Bombers are immobile defense mechanisms, so obviously they've got defender in Magic. The Vibrant version is another recommission creature, while Blue Screw Bomber gives us another mill factor. Neither one is great, but I do think that Vibrant Screw Bomber in particular would be very playable in a limited situation. An 0/4 creature blocks a lot of guys early, and he becomes useful later as a way to ramp colorless mana.
Speaking of mana...
One of the cycles I put together for this set is the group of lands above. I had a lot of variations on the "dual land" mentality, and in fact I think this set is a little bit weaker than the recent iterations (shock lands, scry lands, etc). But it works into the set, which I like, and it does set up a few rare high-value situations. In my imagination, I see Robot Foundry as the strongest, because black is such a main phase heavy color, but they all have their places. These are the cards I believe I'd most like to playtest, because they could be way worse or way better than I think.
The ETB effect is my attempt to mitigate the upside. The design was to prevent abusive situations, the "infinite mana" possibilities that could happen with certain other combos.
This is another card that I made and I have a hard time gauging its value. It seems to basically give you the chance to overcome getting shorted on mana, but is that better than just having another land? Maybe not. Anyways, it's definitely a large effect, and there's probably some way to exploit it, so boom, rare.
Now, here comes a bigger "boom, rare."
Strictly speaking, Wily Machine Prime isn't a recommission card. But it's absolutely a card that you want in a deck that features some recommission cards. Even in the most basic situation, it's probably a 4/4 flyer for 6 mana, which is good value. But it's a mythic rare, and it's the final boss from the original Mega Man. It's gonna be more than that. It turns all recommissions into boss acts, and gives you a big, big flyer. Wily Machine Prime can break a game open like Kalonian Hydra or Krenko, Mob Boss. And that's how it's supposed to be.
So there it is, the first mechanic from my custom set. I haven't revealed all of the recommission cards just yet; they fit into other card reveals. But hopefully this keyword gets you talking about the set, or the mechanic, or Olympic hockey. See you next time!