Hiding the spell and the action it takes are kind of superfluous to the jumping rule that says “[…] each foot you clear on the jump costs a foot of movement.”
Update: We finished the campaign last night on Friday the 13th (9/13/24). We all got out alive, with the majority of our loot, from the 23rd level, at level 19 (334411 XP 😁), but opted not to fight Halaster in the condition we were in.
Well, technically it doesn’t say your connecting walls have to be straight, just 80 feet long. Not exactly sure how you’re going to make them connect up into a hexagon or star out of “four turrets with square bases, each one 20 feet on a side and 30 feet tall, with one turret on each corner”, but if you’ve got a diagram I’d love to see it. 😆
The spell mighty fortress is very specific about the size and shape of the castle it makes, but not about where walls are connected. Both are 120’ square areas with four 20’ turrets connected by 80’ walls, but the second one you get more interior space and can access your turrets without leaving the outer walls.
You can make it permanent if you cast it 53 times, and by the time you hit level 15, 500gp for a week of downtime with comfort and security is occasionally worth it. Our druid/cleric regularly casts greater restoration rather than wait for me to prepare remove curse the next morning.
I’m in the middle of the 5e version at the moment. We’re level 11 and have reached floor 9 so far. We started December 1st of 2022 and play at least once a week.
But Umbral Sight works with normal darkness too, and if it doesn’t prevent magical or non-magical light from illuminating it, people don’t have to rely on darkvision to see them in that magical darkness (if it’s illuminated by anything). At least the Hallow darkness effect prevents illumination, so that does work for Gloom stalkers, but this is quite literally useless.