MAJOR SPOILERS of 'Return to the Tomb of Horrors' specifics below....
The setup:
I'm a new-to-3.5E DM running a one-shot through the 'Return to the Tomb of Horrors'. My group built 14th-level characters just for this adventure. I've told them the ToH is "the most fun they'll ever have seeing characters die", so they're prepared for the worst.
I am converting from the 1E module, and it has several encounters that don't seem challenging enough for 14th-level characters. I'm wondering how much of that can (or should) be attributed to version differences. As a new 3.5 DM, I could use both philosophical and mechanical advice.
Encounter #2: Ghasts in the Bog
For people who don't know the module, the party's destination is inside a small walled evil city situated within a huge swamp. If the characters approach on foot, they'll have to walk on a firm layer of peat floating atop the swampy water. If they scout/scry beforehand, they see a small group walking across the bog chanting a loud dirge. If they follow the same path and don't chant, a group of Ghasts will attack them from below, thrusting their arms through the ground to grapple. Paralyzed characters are pulled down into the murk and start drowning.
With the ACs and saves these characters have, the Ghasts would barely even register... I doubt more than one of them will get grappled, let alone pulled under. Now, here's a philosophical question: are those Ghasts meant to be a physical threat, or a test to see if the party can deal with the situation quietly so they don't attract undue attention to themselves?
I can imagine ghastly hands thrusting out of the ground they walk upon will scare the crap out of 'em regardless of how much danger they're really in... but are the mechanical differences enough between 1e and 3.5 enough for me to, say, give the Ghasts a few more HD? Or should I let it stand as is and just think of it as a great way to test their mettle and set the 'horror' mood?
Encounter #2: The Dim Triad
For the unfamiliar: The module features three vampires that are notable enough to be given individual names. If the party does not take good precautions while camping in the foggy swamp each night (i.e. magical wards, inside a Mord's mansion, etc.) one of the vampires will sneak up in gaseous form and attempt to coup de grace characters in their sleep. Later, the party will fight the Dim Triad face-to-face inside a somewhat cramped dungeon. In the 1E module the vampires have 8HD.
The night-time assassination would work fine as is. However, those vampires will get pasted in anything resembing a stand-up fight. (Cleric with Heighten Turning feat and a Paladin charisma-monkey.) Were 8HD vampires an actual challenge for 1E 14th level characters? Would it behoove me to add a few template levels to each one to make them a bit more interesting? Or, are they supposed to be dangerous only to the uncautious and the unwary?
My idea was to beef 'em up a bit... make 'em 9-10th level characters (Thamaturgist, Blackguard, Assassin) plus the Vampire template. When they face the party in the Black Academy, they will most likely be buffed and ready with some 'divide and conquer' tactics. I read James McMurray's story hour here on EnWorld, and he made the Dim Triad absolute bad-asses; I'm not sure I want to push it *that* far - I'm don't want characters dead before they get into the Tomb unless they deserve it.
However, I do want to give the party an interesting combat with some enemy spellcasting. Normally, three CR12 opponents are a CR14, but should I adjust them to account for the preparation and/or suprise?
...
So, I guess I'm asking for the ways other DMs have/would approach these issues; I'm interested in hearing the way you think about these situations. Thanks in advance for any tips/ideas.
Wish me luck.
The setup:
I'm a new-to-3.5E DM running a one-shot through the 'Return to the Tomb of Horrors'. My group built 14th-level characters just for this adventure. I've told them the ToH is "the most fun they'll ever have seeing characters die", so they're prepared for the worst.

I am converting from the 1E module, and it has several encounters that don't seem challenging enough for 14th-level characters. I'm wondering how much of that can (or should) be attributed to version differences. As a new 3.5 DM, I could use both philosophical and mechanical advice.
Encounter #2: Ghasts in the Bog
For people who don't know the module, the party's destination is inside a small walled evil city situated within a huge swamp. If the characters approach on foot, they'll have to walk on a firm layer of peat floating atop the swampy water. If they scout/scry beforehand, they see a small group walking across the bog chanting a loud dirge. If they follow the same path and don't chant, a group of Ghasts will attack them from below, thrusting their arms through the ground to grapple. Paralyzed characters are pulled down into the murk and start drowning.
With the ACs and saves these characters have, the Ghasts would barely even register... I doubt more than one of them will get grappled, let alone pulled under. Now, here's a philosophical question: are those Ghasts meant to be a physical threat, or a test to see if the party can deal with the situation quietly so they don't attract undue attention to themselves?
I can imagine ghastly hands thrusting out of the ground they walk upon will scare the crap out of 'em regardless of how much danger they're really in... but are the mechanical differences enough between 1e and 3.5 enough for me to, say, give the Ghasts a few more HD? Or should I let it stand as is and just think of it as a great way to test their mettle and set the 'horror' mood?
Encounter #2: The Dim Triad
For the unfamiliar: The module features three vampires that are notable enough to be given individual names. If the party does not take good precautions while camping in the foggy swamp each night (i.e. magical wards, inside a Mord's mansion, etc.) one of the vampires will sneak up in gaseous form and attempt to coup de grace characters in their sleep. Later, the party will fight the Dim Triad face-to-face inside a somewhat cramped dungeon. In the 1E module the vampires have 8HD.
The night-time assassination would work fine as is. However, those vampires will get pasted in anything resembing a stand-up fight. (Cleric with Heighten Turning feat and a Paladin charisma-monkey.) Were 8HD vampires an actual challenge for 1E 14th level characters? Would it behoove me to add a few template levels to each one to make them a bit more interesting? Or, are they supposed to be dangerous only to the uncautious and the unwary?
My idea was to beef 'em up a bit... make 'em 9-10th level characters (Thamaturgist, Blackguard, Assassin) plus the Vampire template. When they face the party in the Black Academy, they will most likely be buffed and ready with some 'divide and conquer' tactics. I read James McMurray's story hour here on EnWorld, and he made the Dim Triad absolute bad-asses; I'm not sure I want to push it *that* far - I'm don't want characters dead before they get into the Tomb unless they deserve it.

...
So, I guess I'm asking for the ways other DMs have/would approach these issues; I'm interested in hearing the way you think about these situations. Thanks in advance for any tips/ideas.
Wish me luck.
