UndeadHalfOrc: dtgreene as always your knowledge is appreciated.
Something I forgot to mention:
Monster regenerator huts don't just regenerate the 1 monster it names,
but other monsters on the same map too.
The Where Are We mod agrees with me from their description of the huts.
Ogre dwelling kept regenerating sprites early and I didn't know why then.
But way more dangerous are the vulture rocs in E4. I had slain a dozen barbarians
on my first visit but left their hut intact. Imagine my dread when I came back later
and found
vulture rocs freely roaming the desert. Normally they are only found guarding treasure spots.
Respawning monster spots are typically linked to lairs; as long as the lairs are still there, the monsters in question will respawn. However, there's the occasional case where the developers messed up, and destroying the lair doesn't prevent the monsters from respawning as they should.
I don't know whether there are any lairs with inverted logic, where monsters won't respawn as long as the lair still stands, but will respawn once you destroy the lair.
By the way, if you cast Half for Me on a character whose HP is above their maximum, the spell will deal negative damage to the caster. This can raise HP above its normal limit (and yields exponential growth if two characters cast it on each other), but since it's technically damage, an overflow into the negatives will kill the character. (This is unlike a certain fountain in Swords of Xeen that gives HP without limit; if that raises your HP to the point of overflow, you won't die or fall unconscious, despite having very negative HP.)
HP/SP overflow *might* be possible with the way fountains work in MM3, where if even one character's HP/SP isn't above the maximum, the whole party can benefit. This was fixed in MM4, though I note MM5 has one event that, at a certain time each day, gives everyone 1800 SP without limit. (I'm wondering if that can overflow.)