The lack of comments in this excellent gallery is incredible-- and I must rectify this at once to say that the Duke of Venomania piece actually made me smile and search the long buried song in my iTunes. Your choice of gif on that tag made me laugh haha!
I really really love this piece in particular:
https://i.imgur.com/vPihM5m.png and that has nothing to do with the fact that I'm a sucker for space effects in my tags. I do feel like a little more could be done- text or sparkle c4ds, but the colors are to die for, and I love the positioning of the focal.
I'll focus my comments on the manga colorings though, since there's more room for improvement there than on your tags which look very nice already. It's clear that you have excellent coloring skills based on the Undertaker piece- in which the shading is still a little simpler than I would favor myself but still looks really polished. It fits the Kuroshitsuji style perfectly, but I wonder why the Fairy Tail pieces are a little more lacking in comparison...? Like the black doesn't have any highlights or anything and the hair also lacks shadows... But I digress- they were posted in June and it's been a long time since then! I'm really looking forward to seeing newer colorings someday!
Er, actually I should probably say a thing or two about the new tags since they were posted more recently haha-- I like the second one much more than the first- I feel like the values in the first one are all too similar so it's hard to fish out the focal, and I'm on the fence about that white texture overlay... But I adore the wireframes and I do really like the text placement. I feel like a more grungy and less uniform texture would've done well for the first one!
The second one I actually really like the way it is-- the only thing I would say is that I would've personally preferred a touch more contrast, to bring out the reds against some darker colors-- and perhaps added a little touch in the foreground for something of interest down at the bottom of the piece. But it's pretty on point otherwise, loving it!