As we have the Danger Level more or less solved (except the Cave and level types! Blade help!), there's the added problem of Monster Rarity. Up to date rarity has been controled only by the maxLevel and minLevel of a monster. A monster was choosen from the in range monsters. This however is a too big simplification. Some at least basic rarity differences should be in.
A note about difficulties -- similarily to the old system, the way difficulties are handled is that all the minlevels are decreased by the same amount, depending on the diff-level.
I tweaked the maxlevels a little, to reduce the amount of monster types that can appear at the same time. I also introduced rarity -- it doesn't differ much between monsters, but it allows for example to generate more cacos in hell than arch-viles or arachs.
I know you love my l33t OpenCalc skillz so here's another nice chart :P:
This is how the chance are after implementing weight and tweaking max-levels.
The weights are 6 for everyone except:
10 - former human, seregant and captain
8 - imp
4 - arch-vile, mancubi, arachno
The weights function in a way, that they weight the random roll eg. if we had a choice of only arachno, demon and former human (4+6+10 = 20) then we would have 50% chance for former human (10/20 = 50%), 20% chance of arach (4/20 = 20%) and 30% for demon (6/10 = 30%)
DISCUSS!