As much as I dislike the Transformers cards, I have to admit that Soundwave, Sonic Spy // Soundwave, Superior Champion is a masterpiece of design. Casting instants and sorceries from enemy graveyards is already a really fun design space, but requiring that the damage dealt exactly equal the mana value of the spell is absolutely genius. Remake Soundwave with "mana value less than or equal to the damage dealt" and he's far, far less interesting to build and play. Simply make a massive token army, like so many other decks already do, and smash them into people for value. But exactly equal...now we've gotta get big-brained up in here. Galaxy brained.
Maybe too galaxy brained for me, tbh. This is definitely one of the most difficult builds I've worked on. I've got loads of cards pulled out, but striking the right balance seems extremely tricky given that we're so dependent what our opponents' decks are doing. Some decks will readily give us fodder just by playing. Some will be significantly more difficult to squeeze value from. Some will have 1, 2, 3 mv spells. Some will have big 8 mana bombs.
I've identified the main elements of the deck I want to focus on. So far I have:
-Token generation
-Power manipulation (anything from equipment to combat tricks to sac outlets, to make sure the right amount goes through)
-Mill
-Control (removal, counters, wipes)
-Tutors
-Value
-Ramp
-Lands
Currently I'm thinking of a balance somewhere along these lines:
Tokens-14
Power Manipulation-8
Mill-12
Control-14
Tutors-4
Value-4
Ramp-6
Lands-38
Of course there's overlap with some token makers milling, some control spells making tokens, some power manipulation adding control, etc. so the actual numbers will likely be a bit better.
Alright, I'll go into some thoughts on each category.
Tokens - The big thing here, of course, is tokens that can reliably connect. Unfortunately there aren't very many unblockable tokens around. Flying is by far the most common option, though of course it's unreliable. Soundwave does provide two very nice ones - Ravage is extremely rough to block, and Laserbeak is a great place to load up equipment/auras/etc with limited risk of blowout. So honestly there could be a build here that doesn't use any token production at all, and just focuses on manipulating the power of those two tokens. It's worth noting that Soundwave can trigger once for each opponent, so only having two tokens does prevent you from getting the sweet triple value. But it's also worth noting that, from what I can determine, a pretty significant majority of the most popular commander spells cost either 2 or 3, with a decent number at 1, some at 4, and not many at 5+. So honestly, you could almost consider going with no tokens OR power manipulation. Putting a Sword of X and Y onto either token could easily put them out of range of most targets. Based on that, I think it's probably worth having some fine-grained control with 1/1 flying tokens, in order to cast the 1-drops and also to add to Ravage/Laserbeaks damage in small increments, though with a focus on the ravage/laserbeak tokens. Note that you can accidentally brick yourself if you're on the robot side with no way to produce tokens, though.
Power Manipulation - As mentioned, a big risk here is overshooting it. Especially with a token-heavy low-evasion build, your opponent could have a lot of control over what you cast based on how they block. So running sac outlets actually could be very useful if they decide not to take an obvious block, in order to prevent you from hitting something they don't want you to hit. One thing of particular note is first/double strike - it could screw you up pretty badly if you transform into the cassette player side, and then can't trigger for the regular strike damage. Casting an instant between strikes will solve the problem, but an even better solution is to hit multiple opponents with first strike damage - the first trigger resolution will flip you to the cassette side, but then the second resolution will flip you right back - not because of the robot side trigger (transforming won't happen if it already transformed since the trigger was put onto the stack) but because his cassette side will see you casting an even/odd mv spell from their graveyard. Tricky to pull off, obviously, but it raises the possibilities to up to 6 triggers in a combat.
Mill - This is something I'm putting more and more consideration into. A lot of decks are fairly instant/sorcery light, and we absolutely live and die by having targets in enemy graves. Dedicating cards just for the chance to add some castable fodder seems kinda stupid, but when you consider something like Maddening Cacophony that can add more than a hundred cards, it starts to seem very reasonable. I do think we probably want to focus on cards that are very efficient - Millstone doesn't exactly seem worth it. But throw out a Ruin Crab on turn 1, and you'll have dozens of cards in graves by the time you're ready to connect. A few important questions - how much should we value symmetrical versus asymmetrical mill - more opponents milled means more potential for getting multiple casts in a single combat, but it's also likely that some opponents will be significantly better than others in terms of likely targets. Some of this is kinda moot because in modern design we rarely pay any extra for symmetry, but there are some redundant options that are targeted. We could either accept some of the targeted options, or potentially focus more on tutors in order to get the mega-bombs like cacophony.
Control - not much to say here, I'm pretty familiar with the Esper control suite. As per my evaluation of the likely targets matching up fairly well with ravage/laserbeak, I wonder if the deck could be built as almost pure control and trust Soundwave to generate value on his own. But then I think that about basically every deck. One other note - it's basically impossible to keep Soundwave protected from your own board wipes by leaving him as a noncreature artifact, since casting any spell will mandatorily flip him back to the robot side. So no synergy there, unfortunately. If you can hit one in an opponents grave, though, you can make it work. Most likely light on wraths and heaviest on counterspells since that's something we can never get off soundwave.
Tutors - not obviously necessary, except that I think mill especially is a somewhat shallow pool with some really really strong options and a quick drop-off in quality. That sort of pool incentivizes using tutors to find the good ones. And ofc few decks are made worse by a demonic tutor. Probably only running the very very good ones, though.
Value - low priority since that's what our commander is doing already. But a few of the stronger pieces could be a good idea just to keep us topped up with control pieces. Could maybe focus on land-generated value to reduce the footprint here, since we shouldn't need much.
Ramp - We're only really interested in ramp early, to get out soundwave on turn 3 (maybe 4 for the B side) and start making tokens, so it's a low priority. There are some lands which can help, though the color requirements do make it harder.
Lands - Probably relatively high on lands since we can't get them directly from soundwave's value generation. 3c so fixing is fairly high priority of course.
That's where I'm at at the moment.
So the big questions are:
-is it worth dedicating 10+ slots to token generation, or should I focus more on the built-in tokens and manipulating their power?
-should I use splashier equipment that risks putting targets out of reach, or is fine-grained control like Kamiz, Obscura Oculus a better fit?
-how many slots should be dedicated to mill, and should those slots mostly be tutors to find the best mill, or should I use a wider swath of single use and repeatable mill to counter graveyard exiling?