Hell of Copper Pillars is weird

[McFrugal]

v1.1.3
If I mine some copper and make hammers, I make a little progress then I get a message about the chains breaking and the hell lord coming to investigate. So that's one problem, the chains "break" too early.
Second problem: I immediately get kicked out, with a message about having taken too much damage. I hadn't even challenged the hell lord yet.

This is without having done any other progression in hell yet. I think on my first attempt at hell (on a much weaker incarnation) I got the chains breaking message without having merged any hammers at all?

[McFrugal]

Upon further investigation, it seems that when I merge two of the 1 strength hammers together I get one with 2000 strength, rather than the obviously intended 2 strength. This immediately fills the progress bar. I don't know why I was dying before challenging the lord. Fighting the lord is very annoying since you're not allowed to use your real weapons and the copper hammers have low durability so they break instantly. I'm guessing you need hell followers or something to boost the weapon's durability.

Now that I think of it, the first attempt probably had auto-merge on, and I must have pushed the hammer button at least twice.