My local gaming shop has an old copy of the Psionics handbook from D&D 3.0, I know the name of the book for 3.5 is Expanded Psionics but I'm really a big fan of supporting local businesses and I need a book on Psionics so I am wondering if the Psionics handbook is compatible with 3.5 or are Psionics broken for 3.0? Also what are the differences between the books?
An unofficial FAQ created by the community on Wizards' forums says the following:
The Psionics Handbook is from 3.0, and is no longer supported. The Expanded Psionics Handbook, despite the name, is a standalone system that replaces the 3.0 system. 3.5 psionics differs from 3.0 psionics far more than current edition magic differs from AD&D 2e magic. The consensus on these boards is that the changes were for the better.
This thread has some actual play feedback about the differences between the two. The consensus seems to be that 3.0 psionics were ridiculously weak (weaker than the base classes) with the exception of a few gamebreaking powers. Things seem to be better balanced in the 3.5 version and in general, much better received. Also, two new classes were added and some new psionic races.
From what I gather, you could use the 3.0 rules with 3.5, but given that the 3.5 rules are superior and released for free online, I'd say it's probably not worth doing.
No, it's not. Officially, 3.5 includes everything from 3.0 that did not get a 3.5 update, but psionics did, in Expanded Psionics Handbook. In fact, nothing changed nearly as massively from 3.0 to 3.5 as psionics did.
In fact, the Psionics Handbook wasn't really compatible with 3.0, either. It involved a lot of ideas that might have been nice in a stand-alone game, but that didn't work in 3.0 and suffered for trying to make them fit. Which is to say, the 3.0 Psionics material was terribly designed to begin with, which is why it got such a massive overhaul.
On the other hand, the Expanded Psionics Handbook is both excellent (one of the best books published for 3.5), and totally free since it is a part of the System Resource Document.
I have played with both systems, and am led to conclude that with a little tinkering, you could insert a 3.0 Psionics Handbook character into 3.5e, making only the changes necessary where things like Damage Resistance 5/+5 become 5/adamantite, 5/magic, etc.
They are different character classes and the designs are radically different, but the adventures and monsters, in general won't care. In terms of raw power, the 3.0 psions have their tricks, just like the 3.5 psions, but they are totally different tricks, with maybe 20%-40% overlap.
3.0 Psions have access to persistent power without using a 3rd party author, and it is cheaper, but they don't have the Wilder Class. Instead of Psionic Focus, you have Reserve Pool, and some feats simply cost Power Points instead of costing Psionic Focus, so you could have several feats active simultaneously in 3.0. Inertial Armor was a feat that granted +4 AC as long as you had PPs, and became Deflection Field, in 3.5e, while the term Inertial Armor was applied to a scalable Mage Armor variant with AC as high as +16 with enough power points and manifester levels.
Telekinesis The Telekinesis in 3.0 is superior to the telekinesis in 3.5. Both editions have several telekinesis powers, but in 3.5, you are stuck using Otiluke's Resilient Sphere as your heavy lifting power. Otherwise, you are stuck with around 250 pounds + 25 pounds per additional manifester level/pp in 3.5e.
So to put that in perspective, a 20th level Psion: Kineticist vs. a 20th level Psion: Savant.
3.5e 20th level Kineticist, 15x25 + 250 = 625 lbs telekinesis, 20pp. range: ~300 ft, speed: 20ft/round, Creature Damage: 1d6 Giant Boulder Damage max: 25-25d6, 1d6/25 lbs
3.0e 20th level Savant, True Telekinesis, 20x500 = 10,000 lbs, 17pp. range: ~1200 ft, speed: 100ft/round, Creature Damage: 16d6 Giant Boulder Damage max: still 1d6/25 pounds...
3.5e Psychofeedback allows you to shuffle your stats for ability burn damage, up to your level (so about +20, or +10 to an ability bonus). The advantages are that you have the full bonus for up to 20 rounds and only have to pay 9pp. The disadvantage is that it takes days to recover the ability burn.
3.0 Psychofeedback cost 2 pp per +1 bonus from Str, Con, or Dex (i.e., 1pp was basically +1 str, dex or con, in terms of stat bonuses) that you spent each round for up to 10 rounds, and could shuffle each round, spend more, or less. The advantage is you can replicate the attribute bonuses of a dragon, like +17 or better. The disadvantages are half the duration, and potentially burning through all of your Power Points before even that happens, depending on how you interpret how many PP you can spend per round on this power.
A lot of powers are identical. Like Genesis and Apopsi, or so similar you wouldn't notice. So the two versions of the class interacting on the same table would be pretty unremarkable. The feel would be similar. If you were careful, no one would even notice the edition difference.
Some of the powers in 3.5e are cantrip 0 level in 3.0. Many were reduced, nerfed, or renamed.
3.0e for example, has Steadfast Gaze, a 1st level power rendering you immune to gaze attacks for 10 minutes (100 combat rounds) per level.
3.5e counters with Synesthete, a 1st level power that can feel light or feel sound, and one of the options renders you immune to gaze attacks for 10 minutes per level. But throws in +4 to spot and search. It doesn't say whether feel sound makes you immune to any verbal, siren, or sonic attacks.
Now, 3.0 Psions have drawbacks. For example, there are 9 different Astral Construct powers instead of one that is augmented like in 3.5e. That means it takes a lot of spell/power slots to be a shaper, something a 3.5e wilder would balk at. The 3.5e Psi Crystal provides higher skill bonuses and better options and variety than the 3.0 Psi Crystal. For example, the Concentration Bonus for a single minded psi crystal personality in 3.0e is +1 (Psionics Handbook p.11), while in 3.5e the same personality concentration bonus is +3 (XPH, p.23)
Additionally, while the 3.0 Savant/Kineticist gets an uber godlike telekinesis power, they do NOT get Bend Reality or Reality Revision powers available to their 3.5e cousins.
I would therefore rule it this way: After you fix all the fiddly bits like the changes in Damage Reduction from editions, Treat the 3.0 psions the same way you treat the classes from Complete Psionics, like the Ardent with their Psionic Mantles, and the Erudite with their cleric/Wizard-like memorization/selection of powers each day.
Because of the sheer number of powers that are virtually identical, and because psionic/magic transparency rules are identical, hit dice are identical, and so many skills are nearly or literally identical, I don't see a problem with using it in 3.5e, as long as you take the few minutes to make adjustments.