So I'm running Wave Echo Cave in my homebrew FR campaign, complete with the same lore (different location though). The party's characters are 3rd level (there are 3 of them), so they are a bit weaker than the adventure recommends (this isn't a problem, I've weakened all the encounters). Anyways, I was thinking of using Venomfang as the BBEG in the dungeon instead of Nezznar. I'll put him in area 18 (and add a secret entrance in the back that he got in through). The party will be provided with scrolls of mass protection from poison and fireball. Areas 19/20 will have the cultists from Thundertree in them. So, does anyone have any tips for this dungeon, either about it as written or my variation of it?

 The flame skull will likely mess people up if it casts fireball. So I would either fudge the roll (Maybe make the damage d3s instead of d6s. Or come up with a number in advance), not use fireball, or replace the monster.  Remember Venomfang traditionally runs away once he takes 70 damage. Being a CR8 monster, he could easily wipe out level 3s, even an entire party, with a single attack.

I would come up with explanations for a lot of the more fantastic elements of Wave Echo: like the magical scarring on the ceiling. In my experience, the players will want to know more about that. Also,  think about how a dragon is going to get into room 18. You'll also need to think of something to go in rooms 19 and 20.

I think there's a lot you could do with Mormesk in area 14. For my players that was actually the last person they faced in the quest, and I just had killing him cause all the other Undead to de-animate... the players really wanted to clear out the mines and rather than go through a tedious crawl eliminating some relatively weak zombies and skeletons I just let Mormesk be kind of the lynch pin that's keeping all the other Undead active.

Quote from Verenti >>

 The flame skull will likely mess people up if it casts fireball. So I would either fudge the roll (Maybe make the damage d3s instead of d6s. Or come up with a number in advance), not use fireball, or replace the monster.  Remember Venomfang traditionally runs away once he takes 70 damage. Being a CR8 monster, he could easily wipe out level 3s, even an entire party, with a single attack.

I would come up with explanations for a lot of the more fantastic elements of Wave Echo: like the magical scarring on the ceiling. In my experience, the players will want to know more about that. Also,  think about how a dragon is going to get into room 18. You'll also need to think of something to go in rooms 19 and 20.

 Yeah, I'm gonna nerf that fireball; it nearly killed my 4th level party las time I ran LMoP. I forgot to mention, I will be supplying the characters with scrolls of mass protection from poison and fireball, so they won't just die from Venom's breath weapon and will have a better chance of beating him. I've run the Venomfang fight with said scrolls many times, and the characters have always survived (if they coordinate and think up a good plan). Venomfang will have a secret entrance at the back of area 18 that he got in through (again I should have put this in main post). I'm gonna put some Cult of the Dragon cultists in area 19, and area 20 will be their headquarters. 

I'd make sure they know there's a green dragon ahead, and that those types of dragons breath poison. Otherwise, they'll get wiped before they realize they need to use the scroll.

Quote from Xalthu >>

I'd make sure they know there's a green dragon ahead, and that those types of dragons breath poison. Otherwise, they'll get wiped before they realize they need to use the scroll.

 They all know that green dragons have poison breath, and they will learn of the dragon ahead of time.