What CR Should This Be?

[Fable Wright]

In the semi-near future, I am planning on running my players through an Undead-infested town run by a Skull Lord (MMV p. 154). For plot reasons, the Skull Lord and a number of its undead servitors are going to have the Spellstitched template. While browsing through the potential minions, I stumbled across something terrifying. Serpentir (MMV, p. 158) are CR 4 (barely) intelligent Undead with Wis 16 and a nifty little ability called 'Dual Actions,' which allows them to take 2 standard and 2 move actions in a given round, and are among the creatures that a Skull Lord can animate.

According to RAW, this abomination would be able to act twice in a given round, can cast 2 4th, 2 3rd, and 4 2nd level spells in their one encounter against the PCs, have blindsense, 50' movement speed, a 20' Climb speed, two Move actions to use them with, a decent melee loadout if the spells run dry, with feats and resistance to Command Undead in addition to Desecration and Corpsecrafter bonuses. It has a listed CR of 5. Add 4HD and 1 CR, and it can take Quicken SLA as a feat. Somehow, opening combat with Black Tentacles, double CL 12 Scorcing Ray, and Enervation on a 126 hp grapplemonster seems a bit out of proportion to the other CR 6 monsters out there.

While there's a good chance I'm still going to throw them at the party wholesale anyway, I'm curious: what CR should the Spellstitched Serpentir be with that loadout?

(Also, this is a PC-accessible monster, with just a CL 10 Create Undead needed for the base monster. That's 1650gp for the scroll, 400-600gp for the gem, and 1000gp + 8000xp for Corpsecrafting. Horrendous abuses for everyone!)

[shylocke]

Yeah. Some monsters can be unfair if used right. Look at the nimblewright golem in mm3(I think). As for serpentir.add 2 cr

[Fable Wright]

Yeah. Some monsters can be unfair if used right. Look at the nimblewright golem in mm3(I think). As for serpentir.add 2 cr

Why CR 8? Compare with a 8th level Wizard at the same level. Serpentir have roughly half the spell slots below 4th level, but in exchange get two turns per round, Improved Grab with up to 8 attacks per round (and the ability to continue moving unencumbered while grappling), free Quicken on some of their 2nd level spells, some SR, bonuses on saving throws, Undead Immunities, Blindsense, All-Around Vision, and roughly quadruple the HP. Just slapping +2 CR on it seems arbitrary and unrepresentative of its capabilities.

Also, Nimblewright is in MM2, which was known for its rather borked CRs.