Probably not, although it does look ancient and clearly has some sort of power. (Note that obtaining it is not necessary to your adventure.)

I was planning on trying to retrieve the dagger after we get across.  I'm worried taking it might have a negative impact on any trying to navigate their way across the chains, so I figure it should wait.

Do we still have the Augmantium box? If so, we should try putting the Dagger in there, instead of letting it burn up. It might be useful later after all.

If I can grab it I will, but I'm floating on a disc right now without a fly spell.  I may not be anywhere near it.

Note: Since you have moved past the disk room and the ruby antimagic dagger was left in the lava (which is totally fine), your PCs probably will start thinking a little more about the effects of the dagger once they can take a deep breath (figuratively and literally). They will probably realize that it may have affected more than just Tahldar's fly spell. (Note that in the case of the dagger, magic items/spells received a type of saving throw to avoid the effects, as well as a percentage that it would not automatically go off when magic is near.)

Oh, gee, thanks, just what I wanted, losing all my magic items... lol

Tahldar only has his bracers and a magic dagger.  It would suck if he lost the bracers, the dagger not so much.

Kahan has his armor, his mace, the Rod of Absorption (which we never really used to its fullest extent because it still confuses me to this day), his backpack, the portable hole is probably considered magical...

Losing the portable hole would be a disaster!  The rest of the items would hurt, but the portable hole is so useful.  Not to mention all the magic items stored in it we've collected so far.  They'd all be lost.

Well, when you can catch your breath (literally), you can start checking them with a detect magic spell. The more magical it is, the more resistance it has to the antimagic flash, with spells being the weakest (such as Tahldar's fly spell).

I won't bother to close up the path behind us if the gases are coming from this room.

My dig spell is still going. Could I try to seal off the northern passages?

A dig spell enables the caster to excavate 125 cubic feet of earth, sand, or mud per round (i.e., a cubic hole 5 feet on a side). In later rounds the caster can expand an existing hole or start a new one. The material thrown from the excavation scatters evenly around the pit. If the wizard continues downward past 20 feet in earth, there is a 15% chance that the pit collapses. This check is made for every 5 feet dug beyond 20 feet. Sand tends to collapse after 10 feet, mud fills in and collapses after 5 feet, and quicksand fills in as rapidly as it is dug.

It appears that the spell allows you to keep excavating, so I think the answer to this is normally "yes," although breath will have to be expended. However, on the other hand, the floor here is no longer "earth, sand or mud," but is a stone room with stone floors and walls, unlike the tunnel you just came from. So I don't see it working inside the building area, but could continue to work outside it--anyplace there is earth, sand or mud. (As a metagame note, you may need to enter the northern area at some point--emphasis on "may")

EVERYONE:

I wanted to clarify a languages issue for this campaign. Below are the most common languages you will encounter. If your languages in your character sheet do not include one of these, then feel free to delete any that are not in the list below and choose a different one.

Note also the "Foreign Language Proficiency" language, which I created for one off situations where you may want to try to understand semantics, pronunciation, etc.--and its effects will depend on the situation and the roll.

Most common Languages in the Campaign:

Common
Drow
Elvish
Gnomish
Dwarvish
Halfling
Thief's cant/sign language (combined)
Orc
Giant
Illithid (--this one will actually come up in a future adventure)
Allevian
Draconian
Faerie Folk (woodland creatures--faeries, dryads, sylvan, etc.)
Foreign Language Proficiency (This is homebrew. If selected, you have a chance of 1/2 your wisdom, rounded down, to understand part or all of a new language encountered that is not included above.)

I also include "Infravision" in the language category for when there are mixed groups and some things are only visible to those with infravision.

"Ancient Allevian" is a language commonly encountered but cannot be chosen as a language.

I think we allowed me to take a "smattering of Ancient Allevian" from dealing with it constantly but he's far from fluent.

Yes, I think I treated that as the Foreign Language Proficiency or something similar. It wouldn't show up in the Language threads under the "Language Group" line.

I'm sorry but I don't have any spells that can help with the situation we're in.  I'm half tempted to just light a flame and see where that goes...

Is it bad that I thought the same thing? I honestly don't know what else to do here. I'm about ready to start rolling up a new character lol

There are two doors to the south...

My idea is to burn off the mold and determine where the traps are with Kahan's find traps.  Then armed with what traps there are, mechanical or magic, use Leo's skill's to disarm the mechanical and use Geebo or the doppleganger with us to disable the magic traps.

Being careful to avoid the anti magic.  The room we are in looks like it's big enough that we could shuffle ourselves such that we avoid the 10' radius.  Though it would take time which we have precious little of.

We will use the main room to clear us of Geebo's 10' radius.  Prior to attempting to shuffle Geebo past us, I will try to burn off the mold first with two vials of oil so that the NW corner is available.  I don't want to huddle near the eye in NE corner.

I'd like to deal with the mold before Sark or Geebo enter.  That's the first priority since the mold could affect us regardless of anti magic or not.

As for the mold, I also have a 0 level spell "Acid splash" that does 1-3 pts of damage that I assume covers some area.  If the fire doesn't do enough, or cover enough area, to fully destroy the mold I'll try this spell once or twice as well.

I would assume Leo would divest himself of magic and address each chest one by one with Geebo by his side to nullify any magic trap.  Leo checking for and disarming any mechanical traps.

Tahldar is at 'A'.  How about everyone else join me in 'A' and 'B' while Leo/Geebo work on chest 'E'.

What if there's magic items in the chests though? Geebo might disenchant them and they might be helpful for getting out.

Yeah, I thought of that too.  I guess I'd rather risk the magical items than trigger magical traps.