Sacrosanct
Legend
When I mean deadliest, I mean as written, and isn't necessarily due to any one creature, but can also include bad design or environmental hazards.
Also a caveat, I have not ran or played in every 5e campaign, so perhaps Ravenloft is more deadly
But now that we did pretty much the entire campaign of RotFM, with a TPK at the end, I'm looking back and thinking that it might be the most deadly campaign, including but not limited to the following reasons:
I don't mind tough adventures, but ones that are set up where you have to have PCs with certain spells available and prepared or else you can't win don't set right with me, and RotFM seemed to be full of them. The above are just a few.
So...based on what I know, I'd say that this campaign is the deadliest of all of them so far.
Also a caveat, I have not ran or played in every 5e campaign, so perhaps Ravenloft is more deadly
(I played that once, but died immediately when my level 1 fighter in a level 1 party got attacked by a shambling mound in the first mansion and it literally tore me in half).
But now that we did pretty much the entire campaign of RotFM, with a TPK at the end, I'm looking back and thinking that it might be the most deadly campaign, including but not limited to the following reasons:
* In the start of the campaign, it is likely you almost immediately run into Sephek, a CR3 opponent who does an average of 24 damage a round (2 attacks at 12 points each). One average attack will kill most level 1 PCs.
- there is barbarian cave with a magical flame that makes the barbarians within immune to all damage. They will just keep getting up endlessly. The only way to stop it is to cast dispel magic on the flame or to lead the barbarian(s) out of the cave. This is problematic for 2 main reasons: 1. It's pure luck you'll have a PC in the party who can even cast dispel magic, let alone the party figuring that that is what's needed in the first place, 2. It's highly unlikely that the party will know to lure the barbarians out of the cave as a way to stop the regen. It's pure luck dependant on the PCs having certain spells set up and prepared, and having access to them. This is at lowish level as well, so the slot might not even be available
- the lost city of Ythryn is structured where the PCs really need to explore most of the city, however, there is a 50% chance of a random encounter after each area is searched, and 24 hours after the party enters the city, those encounters happen every 1 to 2 hours. That means you get one long rest on the first day, and then it's pretty much impossible to get any more of them. You have to explore an entire city full of encounters, then a ton of random encounters as you're being hunted, all without any rests. We were 11th level by that time, and you're going up against demi liches and archmages and living swords, and all kinds of things. I don't know how parties are expected to survive that exploration
- When you do finally meet Auril, you won't be at full strength for the reasons right above, and she has an ability in second form that freezes you on a DC 21 Charisma failed save. A lot of people from older editions don't realize this, but in 5e, a natural 20 on a saving throw is NOT an automatic success. So any PC who isn't proficient in Charisma saving throws and doesn't have at least a 14 Charisma will always fail. Always. There is no chance of success. Oh, and not only are you frozen, but you take damage each turn. The only way out of that is for your fellow party to destroy a crystal that formed when you got frozen. A crystal that is immune to all damage except fire. So again, the PCs waste turns figuring that out, and if they don't have fire spells, good luck, you're screwed. In our case, me (the rune knight) and the fire druid were both frozen (we both have a 10 CHA so we could never succeed on a save) and there was nothing we could do the entire encounter after that. TPK soon followed.
I don't mind tough adventures, but ones that are set up where you have to have PCs with certain spells available and prepared or else you can't win don't set right with me, and RotFM seemed to be full of them. The above are just a few.
So...based on what I know, I'd say that this campaign is the deadliest of all of them so far.