I am not to blame for your suffering -
@NIGHTBRINGER could have chosen to ignore the Tomb Kings references popping up in this thread. However, as he is a dedicated fan of GW's best undead faction they ever made, the temptation to post more Tomb Kings stuff was too strong...
I don't think
@NIGHTBRINGER chosing to ignore something and not give into temptation is something that happens
Also had another thought about this subject - the way Fyreslayers behave towards others differs based upon their Lodge's code of honour, and sometimes Lodges can turn bad - one case in point is that there was one Lodge that became so addicted to Ur-Gold that they began to attack other Fyreslayer Lodges to steal their Ur-Gold, and were only stopped in a battle where the Lodge opposing them conjured a landslide to bury all the addicted Fyreslayers alive, so in certain instances Fyreslayers can turn bad (but then even though they're so awesome they are mortal and flawed like everyone else). Kharadron have similar attitudes towards those who try to con them out of their aether-gold, so I think it's a general AoS Dwarf trait rather than just Fyreslayers.
The fyreslayers in this particular case weren't presented as suffering from the gold-fever. The background & "justification" we get for their betrayal is as follows:
The fyreslayers have a standing contract with the city. They have been paid before, but lately it's been (somewhat) difficult to pay them as undeath forces keep attacking the caravans bringing the gold to them. Why the fyreslayers don't send an escort for their precious gold is a mystery. Anyways, point being they haven't been paid for their last fight yet, and
only their last fight everything else has been paid. Also, there's the usual bickering cuz the dwarfs want more gold and the city feels like they're being ripped off.
Anyways, the dwarves have a camp just outside the city and since the incoming nighthaunt have been spotted they decided that being inside the city walls was beneficial to them as they like staying alive so they go inside. However their leader is pissy about it cuz in doing so it'l mean he'l "help" the humans despite them not having paid off their last debt yet (ignoring the fact that staying outside the walls would've meant the fyreslayers would've been slaughtered… but you know, details...)
Siege begins, bunch of fighting, fyreslayers guard a particular gate while Idoneth cover the harbor and the SCE + freeguild do the rest. Eventually a wight shows up and says something along the lines of "esteemed dwarf, how can you trust these people? They haven't even paid you for your last job. How many of your men are you letting die (in mostly self-defence, but let's ignore that…) before realising the SCE aren't to be trusted. My lord is far more trustworthy, Nagash Always pays his debts. If you move aside I'l give you this pile of ur-gold. I mean you can totally trust me.". At which point the dwarf concludes he should betray his employers cuz there's a bunch of ur-gold in front of him and that's what any loyal son of their lodge would do. Ignoring the fact that up till now they've been in a permanent war with Nagash for the past few centuries….
To make matters worse, the wight only asked him to move aside. But for some inexplicable reason the fyreslayers go the extra mile and not only attack the city's defenders but
they melt the main keep's gate with their magmadroth's allowing the nighthaunt acces to the stormvault inside that contains some scary nonsense which Nagash will use to become vastly more powerfull so he can horribly murder all living things. And they know this is why Nagash is attacking the city and that they themselves do not want Nagash to have that as they are also living things and would like to remain living... (or well they don't know the exact details of what's inside the keep, but they do know that Nagash wants it for this reason)
Then the local flesh-eater court, which had sworn to protect the city in it's hour of need, arrive and slaughter all the fyreslayers (and nighthaunt) though the scary nonsense is ultimatly released at least the city survives for now.
Anyways, it doesn't seem like the dwarves were conned, or even had particularly strained relationships with their employers. They were missing only 1 payment (while having consistently recieved earlier payments) & they had retreated into the city walls to survive themselves. They were then bribed simply by showing them a big pile of ur-gold. Despite having been at war with Nagash for centuries. And they not only let the nighthaunt pass, but activly supported them in assaulting the main keep on their own accord. Also there was no doubt or hesitation whatsoever once the Wight showed the gold. The way it was presented it also didn't appear like the dwarf was a particularly greedy one or suffering from the gold fever. It was literally just a matter of the nighthaunt saying "look we'l pay you double" and all the dwarves unanimously agreed that they should start stabbing the humans now. Which makes them super untrustworthy allies & should make it impossible for them to get work as mercenaries. Not to mention it rather undercuts their whole system of grudges if they jump at the first oppertunity to betray others..
Also I got it wrong, it's the forbidden power book, not a white dwarf that the story was in.