Some monsters can drain your attributes in melee range, is that not perhaps what happened.

I have also noticed attributes dropping if you don't use them, sitting on the couch every day for example will make a person lose strength and stamina in real life. I believe this is intended behaviour though.

Some pool effects make you lose str and to over time, not immediately. Maybe you've missed a message like this?

Perhaps, I am not sure. What kind of message that would be ? I am usually quite attentive to pool message. If that is the case, the effect is very long lasting...

The loss is definitely not related to innaction nor monster hits... They happen usually when I am walking in the dungeon, not in combat.

"You feel exhausted" message means Str is abused.

These drops come without a message, which is a bit rude in my opinion, I have thought about reporting that myself.

Anyway, when last did your character use his strength, charisma or toughness? Being burdened or above, swinging a heavy weapon, dig, speak to something, taken damage or used natural regeneration?

Well, he was fighting and in strained status. Fighting with a 2 handed scythe.

I was just finishing some trolls that I eat. Got the loss of TOU and STR some 15 paces after the last fight/eat.

Aren't those the attributes that drop with aging, wasn't it perhaps your character's birthday.

Or perhaps a new effect of corruption.

Sorry about all the questions, I'm just trying to eliminate some things to make it easier for development to get to the bottom of this.

Are you hungry? Hunger lowers stats much earlier than it used to.

He ate some Trolls.

I think OP should probably post a savegame. There's lots of things this could be that aren't necessarily the result of bugs.

Too bad I kept playing it ... and die.

Interestingly I stopped losing stats so it was probably a long lasting pool effect indeed. Or aging (was magically aged 18 years).

I just started a new character Drakling priest and I did lose some TOU and other stats at level 2 ... interesting the only meaningfull things was reading books and casting Invisibility...

I am starting to wonder if Invisibility doesnt abuse TOU and CHA...

Did you cast from health? Apparently that is a bad idea now.

Yes, casting from health could be the culprit in both case.

HP casting drains Willpower and Toughness now. Aging decreases Strength. Neither affects Charisma... nothing does besides having your stats drained by a spellcasting monster, AFAIK. Sounds strange.

Does the message "You feel reserved" occur when CHA decreases, or is it just decreasing for no apparent reason?

I got the You Feel Reserved message. That's even what told me something was wrong with my CHA.

Once more the same trouble.

This time I got "Soft-hearted, catch a cold and out of touch with mana" with an elf necromancer. Weird as I can't see how I could have abused my Mana.

But I am invisible as a result of pond drinking and cast with health too... I guess that is one or the other that is abusing the stats.

Casting from HP does affect all three of those stats. The charisma problem from earlier might still be a bug, though.

Charisma is trained by speaking to others, I can think that not speaking will thus reduce it. What I have also noticed with characters that start very high in a particular attribute is that, that attribute will often decrease during the early game and the low attributes will often increase early on. I think it is some sort of balancing that ADoM does there. IIRC it is even mentioned in the manual.

Edit - Here it is:

"Finally, you get a chance to raise (or lower) your attributes. This decision is made by the game and is heavily influenced by your class, your experience level and your actions during game play. There are finite limits to the number of times you might be able to increase attribute scores in this way. Once you have reached your natural potential, no more training of whatever kind will help to increase attributes. Only magical means will further enhance your attribute scores."

I don't think I've ever witnessed stats decreasing out of nowhere. Especially not charisma. It does increase sometimes out of nowhere which is particularly funny if it happens after you've defeated some boss. "You feel very self-confident!" indeed.

On the account of charisma, one of the new corruptions may probably affect it. We have several with no apparent negative effects, like eyes turn black.

I agree, it sounds like HPcasting to me. It doesn't sound like corruption to me. AFAIK, none of the corruptions abuse stats in this manner.

I've never seen stats decrease randomly. There's always a fairly direct cause that can be identified.