Lord of the Unseen.

[ExemplarofAvg]

In planning for my next camapaign I'm making a Shadowlord or King of Shadows, I haven't decided his official title yet, firstly if someone could give me a refresher of how to determine the Challenge rating of a group of creatures or characters, that would be helpful, I intend to make this a very difficult challenge but not a TPK. The Build goes something like
Human Paragon 1/Cleric 2/Master of Shrouds 10/Shadowdancer x (These will be tossed in to taste, Skill are gained through the Human and transferred along the rest of the build (Free Adaptive Learning, Yay) The main goal is to pump out shadows, From Summon Undeads to Master of Shrouds Summoning, to Shadow Companion, he's just going to kill things. As far as domains I chose the one that lets you control more Undead (can't remember what one right now) but I don't have an idea for the other one. Also Feats, Shadowdancer only needs three Master of Shrouds needs two. So that leaves one open, and possibly others depending on what the challenge rating ends up like. The Party contains 3-4 level 10 characters.

Rough Summary to avoid Textwall.
Figure out group challenge rating (3-4 Players Lv 10 Party, Optimizers)
Figure out one more Feat
One more Domain
Ways to get more shadows?

[Diarmuid]

For calculating multiple monsters/NPC's into a single encounter see DMG page 49.

[ExemplarofAvg]

For calculating multiple monsters/NPC's into a single encounter see DMG page 49.

Thank you, Any help for players?

[Fouredged Sword]

Players are tricky to guage. The "CR" of players varries based on thier strengths and the situation + how prepared/smart/clever they are. A good judge is how high of a level wizard they can beat. A wizard lets you pull out your optimisation level to where you want it to be without too much trouble. A group that can beat a level 15 wizard can normaly handle other CR 15 encounters of comparable optimisation.

[Diarmuid]

A party is generally assumed to be 4 characters of the same level. The level of the characters is the "Character Level" referenced in Table 2-6 on page 38 of the DMG. If your characters are optimizers, there's no real formula to determine if you should inflate the party's "Character Level" for purposes of determining what level encounters you should throw at them.

In theory, a level 10 party (4 lvl 10 chars with standard WBL) should expend approximately 25% of their resources taking on a CR10 monster/encounter. If you think that would not be the case you can adjust as you see fit.