I've dug through a lot of corners of the web to find good places for high-quality 'Helltaker' adult artwork, so here's what I trust and why.
First, if you want polished, high-resolution pieces and you care about supporting creators, start with artists' personal pages—Pixiv and Twitter/X are my go-to. Many artists post previews on Twitter/X and put full resolution, uncropped files or prints on Pixiv, Patreon, or Gumroad. Searching tags like 'Helltaker' plus 'NSFW' or 'R-18' on Pixiv surfaces a surprising amount of well-rendered stuff; filter by popularity or follow links from an artist you like to find their commissions and shop links. Patreon and Ko-fi often give you access to exclusive high-res galleries, step-by-step process shots, or alternate poses that you won't find on free image boards.
Second, if you prefer imageboard-style collections, boorus such as Danbooru or Gelbooru index a gigantic range of fanworks with tagging that helps you find specific characters, poses, or themes. Use caution there—tag hygiene varies and resolutions differ—so check artist credits and follow back to their galleries. Reddit has niche communities (look for NSFW-marked subs) and artist-run Discords where people post commission openings and hi-res scans.
Finally, if you care about originality and quality, commissioning is unbeatable. Reach out respectfully with clear references, settle on a price, and ask for the resolution or file type you want. That way you get something unique and support the artist directly. Whatever route you take, always respect licensing, credit the creators, and avoid reposting without permission — I like the work more knowing the artist is getting proper credit and maybe even a tip or two.