Are "X" and the Blacksmith not Compatible?

[Cahos Rahne Veloza]

I've been replacing one of my DMs on my X T N DM DM DM party for Blacksmith for my current runs so I can easily get him to level 50. However as I idle the game I always find "X" dead when I check up on my party before I end my runs. Granted I'll just forget the blacksmith once he's at level 50 already as I am happy with my team setup. Anyway, what's the deal here? Why does X die with blacksmith in my party?

And FYI, X never dies in my defacto party, which is why I'm finding this strange.

RFE - Addendum:

I used my X T N DM DM DM party but replaced X with the Blacksmith and no one has died on my most recent run. So what gives? ???

[HeraldOfOpera]

It sounds like it's the third darkmage that turned out to be needed.

[Cahos Rahne Veloza]

Okay I did a longer, five hour, run with Blacksmith T N DM DM DM and this time both my thief and Nurse died inexplicably. Man I can't wait 'til I get this worthless Blacksmith to level 50 so I can finally unlock his stupid Class Relic and be done with him. My X T N DM DM DM team can do upwards of 12 hour or more runs WITHOUT anyone dying. And I thought the Blacksmith WAS SUPPOSED to give out good buffs, apparently not :P He's kinda made my Full Damage Reduction Gear pointless.

[Cahos Rahne Veloza]

After a few days mulling things over, I think I know what's screwing me over. It's the Damage Reflect Stat. Whenever the Blacksmith, whom I've finally got to level 50 so good riddance, or I equip the new Widowmaker Hammer weapon on one of my heroes, not just the Blacksmith, and I idle the game I woukd come back to see that one, not just X, or two members of my party had died. But if I just keep to my all Damage Reduct gear, sadly X can only equip three silver necklaces, including the new claw sword and that Damage Reduct Wand, my heroes stay strong all thtoughout my long idle runs. I can even equip one of my heroes the new cleansing wand and another the Midas Sword without causing any problems. So yeah, Damage Reflect seems to be bad for my party setup.