With this latest update rebalancing skills and spells, I took back to Arcade mode to give a whole lot of testing through their relative power levels. First of all, it's very impressive how many options are accessibly viable as Flamethrower previously was. Most shockingly I found Ice Nova to be extremely capable in damage and also very safe despite requiring near-melee ranges. Following are extensive thoughts on everything I gave particular attention to.
Smash!: I agree with previous posters that this skill is now extremely strong. I don't think it particularly warrants a nerf in damage, though. It does require some amount of skill in terms of positioning yourself (an added layer of difficulty when Arcade mode can get very hectic) especially if you want to get the three hits on the orb. After extensively playing magic after I played with Smash!, I now feel like a nerf to its EP cost might be warranted. Fundamentally, the skill hasn't changed much except now it's accessible for fighting bosses and is secretly now the go-to 2H Ranged Attack option.
Ice Spikes: This is a spell I particularly enjoy. On my Normal Story playthrough, I spent a significant amount of time primarily using this spell, and the damage up is a greatly welcome addition. The EP cost is something I don't feel much towards in Story (with the ready accessibility of Spirit Potions) but in Arcade Mode it brings the spell from unusable to decently usable. Its damage still feels a bit on the lower end, but it covers a decent area and brings utility. I'm not sure if it's good enough to make a primary spell out of yet, at least in terms of Arcade Mode.
Ice Nova: Holy shit. I think this thing has serious potential to become as omnipotent as Flamethrower previously was. Its damage is a little low, but starting with this spell and increasing your chance to Freeze means you can walk in the middle of any group of enemies and freeze them all. It's actually hilarious how much I was able to ignore defending because of its 100% Chill and ~60% Freeze, meaning anything walking up to me suddenly couldn't attack me. Freezing Beehives is the most satisfying thing I have done in this game by far. Its damage might taper off too much towards the end of Arcade, and I didn't try it at all in Story, but the utility this spell can bring is absolutely stellar. The best part is, if you only use it for utility, you don't need to worry about damage, making it a one-point wonder even in ATK builds.
Frosty Friend: At first I thought it was a serious nerf for Arcade Mode but dude does some wonders now. For all those words I just wrote about how amazing Ice Nova feels? Frosty Friend competes with it in crowd control capabilities just through sheer autonomous killing power. However, presuming its damage scales off of MATK, probably not usable for ATK builds like Ice Nova would be.
Chain Lightning: The damage increase makes the "Lightning" part of this spell appropriate, but the "Chain" part still feels a little bit underwhelming. Unlike Blaize before me, I struggled to have Chain Lightning take off. Even getting decent drops, I had unique struggles with the spell. I frequently fell on a threshold where the first burst would be just shy of killing an enemy, requiring a rebound that sometimes never came. On the other hand, the rebounds felt ineffective at doing much more than interrupting enemy attacks. Against bosses, its damage still felt a little bit on the lower end - but I never took it further than F06 so I don't know how well its damage scales into Gold Charge for Arcade mode.
Focus: I don't think scaling with EP Regen is really a great idea. In Story mode, with the accessibility of Spirit Potions, I never really felt pressured as far as EP went - if I wanted to sustain my EP for spamming spells, I could make it work. Focus would then be most effective in terms of EP/s recovered, but in practical terms utterly unnecessary. On the other end of the spectrum, in Arcade mode, running out of EP can be a serious bottleneck in clear speed for spells, and EP Regen is difficult to find with the lack of guarantee of the few items that have those stats. In this case, when Focus makes the most sense to grab, it's the least useful? I tried it a few times, but honestly it felt so weak every time that I ended up not using it in favour of basic attacks anyway.
Fireball: This was the latest one I played with. I poked around with it in Story mode, but I was incredibly doubtful of its efficacy due to it reliably only hitting one target. Sure, once in a blue moon enemies will line up their hitboxes just right that you can hit two, but let's be real: It's a single-target spell. When compared to Whirlslash or Flamethrower, it seemed on paper that it would be quite useless outside of bosses in Arcade Mode, and points being precious, it wouldn't be worth spending on...
So I beat Winter with it in one attempt. Mind you, previously, my best record was F09 with Flamethrower. lol?
It still has serious flaws. First of all, surprisingly its power is in the fact that it's so strong that you don't need to charge it up to one-shot most enemies. I consider this a flaw because it's kind of unintuitive compared to everything else where you pretty much always want to do a full charge. This is, in part, of it having no area capabilities. I mean, I guess Gold Charge does something, but why bother when you can just lob out a no-charge Fireball and still one- or two-shot enemies from the other side of the room? Second of all, its hitbox is kind of small, and I felt it occasionally didn't match its new graphics. I'm pretty sure it's one of the spells with "Easy to Use" but ironically for me it's much harder to aim than Earth Spike and Meteor. On big enemies, not a big deal, but smaller enemies near-misses were very infuriating. I especially struggled on the Crystal enemies in the Flying Fortress and the Winter and Autumn Fae on F11.
Finally, it's very EP hungry, largely as a result of requiring at least one Fireball per enemy. If you're also running Frosty Friend, you get a whole 2 Fireballs at Bronze Charge! Wowee! And Focus sucks! Never before have I struggled with S Rank Times in Pumpkin Woods and Flying Fortress than running out of EP two enemies in and running around being able to do anything other than lol 30 damage per basic attack.
This also leads into my final thoughts: There's still a divide in usability between ATK builds and MATK builds. While Basic Attacks got nerfed (for good reason) they're still absurdly good - because you get the benefit of making use of 1h and 2h skills and have good basic attacks. When you run out of EP spamming Heroic Slam, you still output decent damage despite the nerf with basic attacks. When you run out of EP spamming Ice Nova, you stare at your frozen enemies and point at your watch, motioning to them how their doom is coming just as soon as you recover more EP. Ranged attacks on MATK weapons was a great idea, but it's still not an attractive option. You have Focus to maybe cut off a few seconds on a full recovery, but that's still several seconds of waiting for EP.
Earlier I mentioned Smash! doesn't need a nerf in damage, but maybe a nerf in EP cost. The reason I mention this is primarily the disparity between ATK and MATK builds. The gap is a lot closer, but a huge reason why Flamethrower was a reliable spell in Arcade Mode previously is that with good damage and a slight amount of skill, you could negate the drawback of relying on EP for damage by full-clearing rooms with one spellcast and then regenerating to full because of your screen transition. If you got good enough with Flamethrower, you didn't sit in a room full of enemies playing dodgeball while waiting on your EP - something I had to do a lot of on my Fireball clear. Now, if this is intended for MATK builds, I don't think that's inherently bad. Cutting the EP cost of Fireball, for example, would have made Winter infinitely easier than my ~400 damage clear. However, ATK builds kind of get the best of both worlds with good basic attacks AND a few decent EP spending options.