Never Ending Trials for sure. Wail of The Banshee, you can practice the levels individually.
With Never Ending Trials, it's all random. You could get easy obstacles up until round 10 sometimes, and then the next time, your easy obstacles stop at round 4. Or you'll fault on a tricky obstacle, and you'll never see it again, or you might, like, 300 retries later.
You have to pretty skilled for that, Banshee's just really boring and takes practice.
No fapping necessary for Banshee