I agree 100% with what HDMD said.

To be honest, I've been skimming through this thread a few times and only today did I notice coffee's edit. I was very surprised that you didn't try to copy some of the awesome stuff he did, because he really gave this sprite what it needs. If you want to make it a powerful attack, study what he did. If you want to make the attack look completely effortless, then you still need to make major changes. Right now, unfortunately, the movement just looks unnatural.

Go the extra mile, bro.

I like where this is going; good readability and volume.

Thanks, Manupix! Your reply is as helpful as ever!

Some things don't work so well though.
Everything looks hyper-glossy, thanks to edge highlights and floor reflexion. That's also the case in the first post 3 versions. Are you sure this is what you want?

Definitely. I want everything to be so glossy and shiny that it borders on the ridiculous. I've been partially inspired by this wolfenoctis piece, but I want to take the shinyness even further.

The outlines / edge shadows don't make much sense. You have 1px-wide highlights on the left side, which are either bevels (should correspond to a 1px-wide shadow on the right) or just sharp edge speculars (no shadow on the right). Wider shadows than highlights aren't physical.
Some parts should cast shadows on others, since light comes from the left: pillars on their bases, left side wall on left side pillar and faraway wall corner.

Thank you, I will take a closer look at the edges and shadows. In regards to the shadows, I hadn't even thought about it untill you brought it up. Hmm, thanks! Probably going to help a lot.

Perspective and proportions: the floor tiles should constrain the proportions of the other tiles, bricks and pillars: right now, each of these seems to play by their own rules. Mostly a problem in the wall tops: the brick lengths can't be the same for facing and side views.

Well... at the risk of being a bit obtuse, could you make a suggestion for the wall tops? I'm really not sure how to solve this problem with the 32x32 grid.

Similarly, in the first post piece, there are 3 different floor tiles perspectives.

That's because I was experimenting and didn't really know which way to go. I was just imitating vierbit's tiles and trying to see if I could learn from them. To be honest, I'm still none the wiser. I know his perspective is sometimes inconsistent on purpose, but I don't understand the way the chooses the floor tile perspective and makes it fit to the surroundings.

Nitpicks: the door 'rings' were best centered; the brick staggering hints at widely variable thicknesses in the corners, mostly on pillars.

Thanks! The bricks are not actually supposed to be bricks, in the sense of solid slabs of rock, as you'd find in a medieval castle. They're more like stone tiles covering a wall. Like marble walls in a palace.

I might prefer the earlier bushes / ivy, provided their colors were closer to the walls so as not too stand out too harshly.

Thanks. I think the first bush looks good, but... it just looks like a bush. Doesn't look like ivy. And I haven't been able to find any good pixel art with this sort of ivy, to learn from. I'll keep experimenting.

Looking at the palette, I find there's many similar looking teals, although I don't really mind that in the piece. Might deserve some tweaking. The doors colors are too different though; a smaller palette might make that less problematic.

I'll see if I can get rid of some colours. What do you suggest for the door? I'm rather fond of the white door, because I wanted something to break with the organic theme I've got going everywhere else. In the end, a lot of the walls and pillars are hopefully going to be overgrown with ivy, and it would be nice to have the door(s) clearly visible and separate.

Like this, Fahrenheit?

EDIT: Fixed silly title.

These are my tiles. I don't have much experience working with tiles, and I'm trying to look at what different people are doing and learning from them, but it's not easy. So I'm just going to post my WIP stuff here, even though I'm still at the stage where I'm experimenting with different approaches.

Everything is WIP. All comments are useful.

The bush is supposed to be ivy, by the way. It's supposed to cling to the walls, but right now I feel it looks more like a tree than anything. And I don't want it to be just a few scattered ivy leaves on thin branches, I want a massive wall of leaves.