Imagine if Mana-burn like in MTG existed as an applicable spell. Would be very funny.
Imagine if someone said to macht or solitar:
"Humanity will perish in a hundred years. Am I lying? Or telling the truth? Would you know either way? One day, stars from beyond the sky will strike and smite the earth. Another, humanity will burn out the forests and fields, and choke to death on the smoke they create. A third, they will war between each other and against demonkind so intensely that the earth is torn asunder in a single strike.
How are you so confident that you can keep humanity alive for long enough to learn? How are you so confident that humanity will continue to exist? One day, another demon will create a pestilence so dangerous that the number of humans remaining is but a mere fraction, a mere percentage point, of their population but a year prior. And then what will you do, when they can no longer be your entertainment? Give up living?
How can you consume and exhaust them if you don't even know how to let them grow and develop? I plucked the forests and fields clean, I chopped the trees until the woodlands disappeared, and now I have met my ultimate failure, and all because I was too shortsighted?
For people who have lived so long to not be cognizant of such risks, it is astounding. You have neither the skill of a rancher to rear livestock and hardly the skill of a hunter to live in balance with the wild. So be it.
In my view, a demon who wished to study humanity would declare that humanity is not to be killed, except by that demon themselves. A demon who kills humanity recklessly is someone who throws out buckets of sand at a time simply because there were no gems upon its surface. No, why bother sifting through humanity when you could simply walk along the beach and toss away all the grains of sand in your path? It's not like your time is important or even your goal is important. But if your goal isn't even important, why live? Why not die right now? Tell me."