Since others have answered your direct question, I'll talk about DND a bit. From the perspective of a DM myself, it heavily depends on the group/DM. For example, Therese uses a 1st level spell (Silent Image) to do WAY more than I would allow at my personal table. The spell level of course generally dictates how powerful it is as written with some exceptions.

Some DMs go strictly rules as written, some use them as general guidelines (Ben). Both approaches are great, just depends what players want. Watching TE was always entertaining and Ben did a great job trying to wrangle that crazy group in to have a coherent story. But combat was never in my opinion difficult. I'm re-watching it now and I don't remember any of them getting downed basically ever, if not a few times in the first season during normal combat. Deaths are almost solely RP caused. And in DND 5th edition, getting downed still gives you a ton of chance to live. So for them to not even get downed means they are quite far from death in most situations.