ToME: the Tales of Maj'Eyal

I actually asked this in chat during the game but I don't think anyone had an answer. Lightning alone is the only spell group with a damage range listed, but when I use it on general critters with no displayed resist (I even check their character sheet) it always does roughly the same amount. Since this is roughly smack in the middle of the range that's fine, but of particular note is one spell that is underwhelming for a different reason.

Thunderstorm.

This is the only lightning spell that does NOT show a range, and gives a flat damage. I would therefor expect that number to be applied, if there's no lightning resistance (or resist all) to counter it... Instead it regularly dumped out about 20 damage when it should have been giving 60 or even 80 per bolt. It was level 5 so for it to be doing the same damage it did at level 1 is rather frustrating, even if it's doing that damage to more than one thing at a time.

Is there a hidden resist i'm not seeing? Is it a bug that nobody really cared enough about to catch? Is it something wrong with my character? I don't get it.

Eh? It says it does 1 to X damage.

Huh. Well, I feel sheepish on that bit. Still, with lightning itself, it usually never varies by more than about +/- 40 points of damage or so. At level 5 where it can range from 100-300 or so, it stays pretty firmly around 200. Sometimes 160, sometimes 240, but never really hits the upper or lower limits outside of a crit or resists, respectively. Granted, earlier on it seems to varry more but once I get some +x% damage it sits roughly in the median. Is this normal?

Both of them are weighted to be generally closer to the mid point.