Hi all, thanks for having me, I created this account to share this one.
I was just having some fun the other day thinking about different types of compounders and it hit me that as a full Feruchemist and Mistborn the Lord Ruler had infinite amounts of Feruchemical power. I always knew this but it really really hit me, so there is no way Vin should have been able to beat him in Era 1, the guy was god tier powerful. Instead, I have a theory that the Lord Ruler essentially killed himself by accident, through the blind use of Chromium Compounding.
There are a couple of caveats to this theory. It works on the basis that as the Lord Ruler had access to all the Era 1 'hidden' metals from his knowledge gained whilst in the Well of Accension, so he would have been always compounding the full range of feruchemical abilities, even if he hadn't let the metals enter circulation or wider knowledge like he did with Aluminium. Including Chromium, which whilst I'm sure would have been crazy rare in Era 1 like Aluminium, you only need to make/find a little chunk to make a metalmind.
Second caveat is that with Chromium Compounding I'm running on a general consensus on these threads that compounding for Fortune works a bit like Felix Felicis in Harry Potter. It is an internal ability like all Feruchemy, so can't change what is actually happening in the world, but rather would nudge you through life in such a way that always leads to achieving your goals. Most people on the threads believe that this would grant a type of quasi-luck-based-immortality.
Yet, I disagree. The Lord Ruler's goal in Era 1? To put a permanent stop to the destructive power of Ruin. If he was always compounding Chromium to achieve his goals, this then leads to the conclusion that the Chromium enacted some kind of unintentional weird suicide, as if wherever the power of Fortune comes from (another discussion I won't go into here) knew he could never personally achieve that goal.
Why? Because his goal was eventually achieved. He could only take the power of Preservation in the Well of Accension, and as Preservation could never have destroyed Ruin as it was against the shards nature, his Chromium Compounding pushed his Fortune towards his own death, and allowed Vin to kill him, in order for the events to unfold that led to Harmonies accension.
So, Chromium Compounding wouldn't lead to lucky immortality. If Fortune were to decide that the best way to achieve your goal was your own death, the Chromium would accidentally push you in that direction. Something to think about.