Two Inferno castles were nearby, providing a decent amount of resources, +3 HP, and a fast town portal to the game master. I overwhelmed my opponent in his super-treasury with 150 demons under an elite creature. Thanks for the game!
I played recklessly and lost. Not only was the map filled with 4 Inferno castles, and my opponent started as Inferno, but he also had a potential path to 2 more, which he took. Furthermore, it turned out that I only had access to 1 castle, and I was met in the citadel, which I didn't enter. In short, on day 131, I took a couple of consecutive tier 3 resources and headed for the treasury. There were plenty of drowned creatures, but no hives or other powerful units to take. I built up to level 4, and ran out of resources. A loss seemed inevitable, and that's what happened in the end.
Thanks for the game!