6dc5455c____The_Coppermind___17th_Shard__Entry
[Chapter] 46 [Entry] 
Ruin's escape deserves some explanation. This is a thing that even I had a problem understanding. Ruin could not have used the power at the Well of Ascension. It was of Preservation, Ruin's fundamental opposite. Indeed, a direct confrontation of these two forces would have caused the destruction of both. Ruin's prison, however, was fabricated of that power. Therefore, it was attuned to the power of Preservation—the very power of the Well. When that power was released and dispersed, rather than utilized, it acted as a key. The subsequent "unlocking" is what finally freed Ruin.
The Hero of Ages/Epigraphs - The Coppermind - 17th Shard
Entry