I know that CR rating should equal the ACL of a party, but I am little confused about it in some respect.
My plan is to have an opposing party fight the PCs through out a campaign always running from them as they stay one step ahead of the PCs.
Normally I would have the Levels be below that of the PCs in order to make it a fairer fight.
But I am a little confused to how CR is calculated after reading some of pre-made adventures. For instance in Curse of the Crimson Throne - Crown of Fangs - Encounter - A38 - PCs are faced against 4 gray maidens (CR 8 each), but the ECL for the entire encounter is EL 12.....
How does this work?
Keep reading , on page 398 of the core rule book , chart 12-3 presents a quick chart for adding multiple creatures . 4 creatures of the same cr add a +4 to the CR.
cheers
CR doesnt scale linearly, is why.
Essentially, each 2 points of CR double the threat.
It might be easier to think about it in terms of the XP each creature awards. The XP award for one CR 12 creature (19,200) equals the XP award for 2 CR 10 creatures (9,600 each), or 4 CR 8 creatures (4,800 each).