I'm glad to hear that the overall concensus is that this creature is snafu'd and that I'm not off the deep end.
ken-ichi said:
For starters, the 2 slam attacks are worthless. Ignore them.
I mention it because a slam attack counts as an "armed" attack meaning it is always armed with an attack only slightly worse than a dagger. Assuming the 'Weaver and a sorceror both ran out of spells or were caught in an anti-magic field, the weaver could likely beat up the sorceror. 2x+9 @ d3-1 vs +5 @d6
Its treasure total for a EL 10 encounter with double magic items is on average 8,450 gp. Much less than that of a 10th level character. Not a lot of nasty that you can get with average treasure.
I include the special magic disk in as "gear". Averaging them out between 10 1st Pearls of Power (10x1k) and 2 5th Pearls of Power (2x25k) gives you 30,000gp. 30,000gp + 8450 is about what a 13th level NPC gets. Sure, it's not "treasure" but what the hey. Like you said, it only explodes when someone tries to use it.
36 hp for a CR 10. Sorcerors have d4s though, not d6s. Pathetic Fort Save. +2 ? Say hello to mr. monk's fist.
He has low hps but he's no more melee than any other caster. And his Fort save is on par with Con<10 sorcerers, like elves. But the hit die size means he's got nearly half-again more hps than a CR equivalent arcane caster (10d4=25hp vs 36hp) Compared to them he's a tank.
Don't forget to bump down the DCs of the schools that it has Focus in, they only get half of what they used to.
It doesn't even have the Concentration skill
You did not mention the SR 21 they have. Only thing keeping them alive from a random fireball or other attack spell.
The lack of concentration is its only potential "gotcha" but I'm used to most casters being bright enough to be airborne or otherwise hard to get to when not surprised. I forgot the SR as well as the +5 natural armor. SR21 means a 10th party has a 50/50 chance of getting a spell through, not good odds.
Since I'm running 3.0 so the Focuses are still an issue though I would choose different schools depending on the spell list.
Seriously this thing would have to have some major prep time to survive at all against 4 10th level characters. A few hits from just about anything and its dead. It is a glass cannon if it cannot be hit then it is great, but the moment the flying monk or fighter is in its face it is gone.
I give this thing about 2 maybe three rounds of combat at most (barring unusual party makeup or favoring encounter setup).
Major prep time? Well, with invis & detect magic at will and the ability to cast 6 spell levels/round I don't think that long. I'm assuming Mage Armor is extended and active and that it remains invisible at all times. One round to put up Shield, probably a stat buff, and Fly. Depending on what Detect Magic says either wait a round to put up a Minor Globe and a Mirror Image or just kick off the battle with a Dispel Magic and a AE spell or Dominate/Charm Spells depending on the 'Weavers goals and the targets defenses. Either way, he's down no more than 2 2nd level spells thanks to his happy grenade-of-power. Maybe toss haste into the mix for the init and other bonuses, though it's not as useful to 3.5 casters as it is to 3.0 casters.