Versailles

If you can handle the half-step patterns with mash, the perceived difficulty drops a bit, but overall I think the stamina requirement is on par with a mid-tier 21. Plus, it demands bracket-step processing skills on top of that.

Even after getting up-rated to S21, this chart isn't even considered easy. The twists are relentless, and then there's the bracket part that can't really be used as a rest part, even if you're good at brackets. This chart doesn't have a lot of breathing room once you enter the hard part. Also for people playing to score, be careful of the slow section, it can mess with your score. Fortunately the chart is in 175 BPM at its highest so it isn't that THAT hard.