N.B.: May contain a touch of rambling and excessive information. :3

C42 & Heart of Ice:
For the most part, the C42 mission hits that right balance of tricky, but soloable with the right gear and planning. I managed to finish it alone without a single revive (there was a close moment or two, though~) using a full loadout of swords (Gran Faust, Acheron, Divine Avenger, Glacius), Elite Quick Strike and Sword Damage modules, and the full trio of Dragon Scale bits. Gun-wise, I ran it in Shadowsun Slicker, Perfect Mask of Seerus, Swiftstrike Buckler, Sentenza, Umbra Driver, Callahan and Supernova, with only two deaths not attributable to lag or other interruptions. However, when I tried to use bombs—multiple times—I couldn't find a gear set available that allowed me to do the same. See the "Bombs" section for thoughts on that matter.

Unsurprisingly, the levels look and sound great, and they are nicely arranged: not ridiculously cramped where it shouldn't be, although perhaps occasionally too spacious for the small number of enemies appearing in many sections. There are only two issues I'd point out, one being that water thrown at gates can splash through the bars and douse water that isn't directly accessible (makes sense, but it can make the room with three buttons on the right behind walls of flame a little easier). The other is that in the room with the antepenultimate party button, the switch sitting behind some breakable blocks can be directly activated with (for example) a Supernova's expanded shot. This may not be a significant issue, but it does seem like it's unintended.

Finally, the enemies themselves are challenging, certainly, but most areas need a little denser population to be truly difficult. As I've seen it pointed out before, the C42 lichens' charge could use a slight alteration to make it not blob a patch of itself right on top of a knight after charging at them, as this and the shield locking that puddles do are the two "cheap" elements of these levels. I am, however, pleasantly reminded of the difficulty T3 Oilers used to present. :> Also, as noted before, the "minibosses" could use a little more power: the C42 colonies are so lethargic that even when engulfed in flames, they don't pose much of a threat. Similarly the heavy scorchers could be more aggressive and have a wider variety of attack patterns than they show now. Having said that, I would dearly love to see these fellows or some form of them replace Trojans and Giant Lichen Colonies in Gremlin and Construct arenas, since those monsters feel rather out of place in those areas.

Summary: a pretty decent level set, probably a little too harsh on the solo bomber, but otherwise still doable alone or in a party despite a couple small issues; could use more enemies and more challenging minibosses; it'd be nice to see those heavy scorchers in Gremiln/Construct arenas.

{EDIT}: After the reboot to add "Heart of Ice", I reran C42 and found it more manageable overall, and the revamped final fight and emergency shower mechanisms were both welcome additions. That final battle feels appropriately dense with vicious critters now, but still reasonable. I'd still kind of like to see those lichens stop spewing that last puddle right on top of players after their charge, but it does add a certain "old T3 Oiler" charm. :>

As for "Heart of Ice", just absolutely fantastic work. Once again, enemy density is one of the important points that almost all of these missions should share, and there are plenty of both fiends and beasts around to keep things interesting. The "Howlitzer-activated tic-tac-toe board" segment was very smooth and I can see parties trying different tactics, both splitting up and keeping together to take down all the foes there. The Trojans make it very claustrophobic at times, and the shard bombs get a chance to show what they can do (although, as noted below, I'd like to see them tweaked a little more). When I came upon the spectator arena, I felt like I was about to play a game of street basketball with an assortment of monsters, obviously a delightful moment, and a fine place to introduce the new 3-hit ice barriers. Again, it's a very well-spaced fight with just enough room to maneuver. Then, of course, the "King Frostifurs"/"Skolver Cubs" (whatever they may be) and Mr. Freeze (dat mission title reference) were a pleasant surprise. The Frostifurs' infinite and perfect shielding was an interesting change of pace, and I'd actually even like to see them be a little more aggressive to make them genuine terrors. Similarly, the big guy himself could use a frontal shield or some form of similar defense so it takes some moving around to take him down. Otherwise, those Vanaduke-esque mace smashes with the ice trails are a neat mechanic, potentially isolating party members if they aren't careful. I was glad to have Dread Venom Striker along for the ride, as it made for a very useful defroster~{/EDIT}

Bombs:
As a preface to this, I'd like to note that I try to spend a lot of time using each of the three weapon branches. I enjoy using all of them and doing so offers flexibility and variety both in solo and cooperative games. I also have crafted most of the "Specialist" armor pieces (Valkyrie, Deadly Virulisk, etc.) and occasionally use them to hybridize in areas where I know it's sensible to do so (like Deadly Virulisk in the Royal Jelly Palace, Valkyrie or Heavenly Iron on Devilish Drudgery depths). I do bomb frequently while soloing, but I tend toward a mix of swords and guns in parties if I'm not acting as a dedicated Vortex bomber or the like; still, I often-enough use damage bombing sets in arenas and other areas to appreciate what damage bombs do well and what problems they can cause a party.

Furthermore, I'd like to remark that until I read the recent post illuminating what the developers think their weapons should be doing and why the shard bombs didn't fit into that framework, I think I still labored under one mistaken impression: that swords were meant for high-risk/high-reward, close-quarters damage on one enemy or small groups and that any ability they had to tackle crowds of more than three or four was supposed to be limited at best so that bombs remain the go-to tool for decimating crowds of more than a few enemies. Despite seeing it specified that swords were designed to be a catch-all weapon type with no limitation on their ability to do AoE-type damage, I dislike seeing them so readily fill every role more than adequately (of note: I usually use sword-optimizing sets when I want to 'get things done' rather than spend time enjoying encounters). In large enough crowds, bombs do certainly seem to outperform even the best-placed sword charges; but it is the infrequency of situations where that balance plays out in favor of bombs that I think is at the heart of my misgivings.

While entirely subjective experience, I find that bombs offer a nice balance of risk, reward and "cleanliness". That is to say, suboptimal damage can be acceptable when a bomb can manipulate a crowd while it damages them (e.g. Dark Briar Barrage keeping Gremlins as a captive audience with its knockdown effect, where Dark Retribution may perform higher damage in less time). In too many situations it feels like wielding a sword, charge spamming or not, encroaches on that territory with very little extra effort. This is not an issue of damage, but rather of ease of use, and that's the main problem I have with the new shard bombs: the damage they can do seems to be in order, but it's still a bit tough to hit anything that doesn't move at a snail's pace more than once. What I'd like to see is how they'd perform if the shards from the bomb had less spread and no knockback on their blasts, or perhaps a somewhat wider spread with a slightly increased radius per shard. The fuse time is probably acceptable, but the hefty delay between the first and second blasts contributes to the problem of making the bomb hard to aim. The point, to me, would be to either make it damage an area more like Nitronome or Big Angry Bomb: either spread thinly over a large radius (so that everything is almost sure to get hit once or twice) or packed tightly into a smaller one (so that multiple hits are easier to land). This is actually how they perform in tight corridors, where the bombs do get a chance to show their potential.

To get a little more information on their current potency, I worked my way into the Citadel via the Arcade and used the bombs there to some effect, but as well as the Deadly Crystal Bomb performed on the Slags, that's how terribly Radiant Sun Shards and the Deadly Splinter Bomb performed on the few present fiends and Vanaduke. This is not to mention the urgent need to fix the stun status' bugs so that it isn't a liability before the Radiant Sun Shards, which many already own and would likely try to use, becomes the full-piercing nightmare it appears to be turning into. Also, I found no reason to use the normal-damage variety of this bomb when Nitronome does their job much better even with the obtrusiveness of the blasts considered, and I'm tempted to say the same of the Dark Briar Barrage/Deadly Splinter Bomb pairing as well. I really like the shard bombs as they are on the live server because they do something other bombs aren't good at: letting the bomber fend off smaller groups in a timely fashion. Swords have options for handling single targets (Brandishes, Calibur, rapier-types) and multiple targets (heavy swords, rapiers again, Brandish charges); guns are geared to do the same with six-shooters for rapid, agile firing and Pulsars/Catalyzers for group attacks. For the most part, bombs require too many charges to make it feel worthwhile, so it'd be nice to have a bomb that causes a very short-range, high-power blast, or multiple average-powered hits.

To summarize that, I like the idea and damage of the shard bombs, but their spread and possibly the detonation times make it an ordeal to hit anything; the normal and piercing damage versions have predecessors that I would almost always rather use; bombing in general feels much harder and riskier for less payout than its counterparts to me, exacerbated by how these bombs are underperforming now (subjective, yes, but true). Thanks for keeping things like testing feedback going, as it's nice to know you've got a dedicated method for collecting such information. :3