Prison Necro- I'm guessing you've already looked at the
Trash HP vs Damage charts. They show that the 50% and 100% HP buff summons get in NM and Hell is slightly larger than the damage buff monsters get. However, Bosses do bonus damage to summons (8x I think), so thankfully very few summons can tank a boss for more than a couple hits. Your Bone summons should do about as well as Decoy, since they do not spawn counters (most summons hurt themselves a lot via counters).
- SC players generally prefer higher damage over survival, so get used to the requests to boost their damage. When they get tired of dying, they will appreciate your summons more.
Questions:
1) I don't have the time right now to examine the monstats.txt text file, especially considering I'd have to calculate the skill damages of a lot of boss spells. I think it was mentioned that decompressing the .mpq of the v1.3a patch does yield the correct set of text files though, if you would like to persue this. From my culling of the boss-rows from monstats (when making the damage charts above), I think I recall that boss damage grows exponentially, for example the damage of all monsters is equal to their level multiplied by a booster, and while Soulmancer seems to have ignored the booster for most Trash (it's around 80% to 150% until Hell, where it's around 100% to 200%), he keeps it around 400% for Norm and I think NM, and about 800% for Hell. This means that a level 90 Hell boss' attack isn't just 50% stronger than when he was level 60 in Norm (due to level increase), but will be 200% stronger (50% from level buff, and then doubled by Booster doubling from 400% to 800%). For example, a boss doing 100 in Norm would be doing 300 in Hell. Your summons will do worst in Hell against bosses because of this (their HP only doubled, but tripling was needed).
2) Since you're making an uncommon build, I'll just give you an io rune. I have had frustratingly good luck with lower level necro gear, which you may select from when you receive the io.
3) Prayer probably affects walls, their graphic is pretty large compared to their footprint, so it's possible that you just can't see the auras affecting them. Since the Bone summons are from the original D2, I wouldn't be surprised if they had some hard-coded oddness about them. There isn't a lot of value in giving your walls Prayer aura though, since if they die you can just recast them, and Prayer wouldn't extend their life by much (if they have around 4k life and survive 30 seconds, a 50HP/2sec (lvl21?) from Prayer would only be like +20%HP, but only if the wall survived 30 seconds).
Psychic Sin- Since you are doing magic damage, you will face relatively low resistances, so unlike most builds your damage will not be significantly affected by increases in difficulty. Still, you should consider a crystal sword socketed with 6 diamonds for the magic pierce. I find that sword bought from Fara in a2 and socketed by Larzuk to be a nice and fast way to boost any caster's damage (their char-screen damage takes a hit, but they will kill monsters quite bit faster). Other than this, I can't think of much else to say for the build. Consider FireBlast for getting the boss heal-timer started, since it shouldn't be affected by ARating, and will start the timer on fire immunes despite being fire damage (as far as I have seen, timers can be started even if the element of attack does zero damage).
Castadin- These builds are very dependant on their gear. At low level, "Voice of Reason" is pretty decent, and of course "Wonder" was designed for the build so it's great at level 65 if you can get the Lo rune. Don't forget that while other builds face high resistances with increases in Difficulty, you will not. This makes you relatively stronger as the game progresses, but you'll never be good for bosses.
Questions:
1) Yes, all crafts are capped at 4 sockets, provided that the item takes up 4 or more inventory squares.
2) For fire element, consider Dragonhelm, and the slightly modified "Phoenix" shield (now level 65). The shield's Firestorm doesn't do much, but it doesn't cause counters either so it's nice, and the shield adds quite a bit of damage to your attack now. The main reason to use it is Redemption on equip. In my experience, the +300%EDamage will not kill you from IM if you are using "Wonder" provided you have some decent DR/MDR. Tiamat's Rebuke is alright before you get a lot of higher runes, but dwindles in effectiveness by the end of NM. Tiamat's probably still has the ICBlocking it received in one of the recent patches, despite what Critter's or Blue's site shows.
Glad to see you're enjoying the possibilities HU opens up on regular D2.