I've been looking for a way to automate sacrificing. I've found the self-sacrifice rituals, but is there a way to sacrifice mobs through automation? I've tried Autonomous Activators, but they don't work.
Yep. Use a Well of Suffering combined with some sacrifice runes on your altar. The Well of Suffering will give you LP for each mob it kills, and the sacrifice runes will greatly boost that. As a warning though, it does require a tier 4 altar to make, as you need Dusk Runes. And if you want to be fancy about it, you can combine it with a Ritual of Containment.