Why Each Class Is In Its Tier
This thread was originally posted is intended as a companion piece to JaronK's Tier System for Classes. It was originally posted as a series of threads by BG user Gr1illedcheese at Brilliant Gameologists/MinMaxBoards here, but because that board has been down for a while, the original is currently inaccessible. But thanks to some work done by GitP user Larkas (thanks Larkas!), I have been able to compile the threads into one source for ease of reference so that this work isn't lost completely. These listings were also posted in JaronK's Tier System thread here on GitP, but I thought that it would be more appropriate to put this information in its own thread, rather than spoilered 10 pages into that thread.
Additionally, thanks to the work of GitP forum members, I will be adding in analysis of classes that were not in the original posts. These new additions will be have their class names put in bold green font, like this, and you ought to find credit for who added the new material as it was in the original thread. If I haven't given someone credit where credit is due, if you want to contribute your own points, or if you notice anything wrong with my posts, please let me know in the thread!
Without further ado, here is what you probably want to see:
Why Tier 1s are Tier 1s
It was brought up that there's no set explanation for why low tier classes are generally less effective. With that in mind, I figured I'd start one. I'll be doing one for each tiers, but I want to get the low tiers out of the way first, because most people know why classes like Wizards and Druids are above average. I'm looking for your input on the classes, and to make this a guide for people new to CO. Thanks to all who contribute in advance.
From JaronK's Tier System For Classes guide, the widely accepted Char Op base power description thread:
Tier 1: Capable of doing absolutely everything, often better than classes that specialize in that thing. Often capable of solving encounters with a single mechanical ability and little thought from the player. Has world changing powers at high levels. These guys, if played well, can break a campaign and can be very hard to challenge without extreme DM fiat, especially if Tier 3s and below are in the party.
Examples: Wizard, Cleric, Druid, Archivist, Artificer, Erudite
A note about an unlisted class: "Psionic" Artificer deserves a mention.
No one has taken an extended look at it.
Psi X / Magic interactions suck.
Psi Recharge available at level 1, more a problem of recharge set-ups, than how Psi Arty does it better.
Linked Power allows Wand-ificer cheese, but on the cheap ... I mean real cheap.
Dorje is a Wand that can have higher than level 4s on it.
Oh hey, Erudite Spell to Power puts spells into the psionics realm.
Oh hey, Dragon #349 put Divine spells into the psionics realm.
If there is a Tier Zero, Psi Arty deserves it, but again ... it's more a Psi X problem, than the class being anything anyone has looked at or bork't. -Awaken DM Golem
Why Tier 1s are Tier 1:
Wizard:SpoilerA quote from an old thread about wizards.This is more to silence those who would claim that wizards are really only powerful when they get to abuse supposed loopholes in the game, such as infinite wishes, spamming major creation or how they presumably always have the "perfect" spell for the job, despite having to prepare their spells beforehand. Even when playing them at a fraction of their capabilities, they should still be able to eclipse the rest of the non-casters. -RunestarOriginally Posted by Ongorth
Cons: You have to pay a trivial amount for spell knowledge above and beyond the stuff you gain for leveling. And if your GM is a major jackass, you may have to put a small amount of resources into protecting your spellbook - an eternal wand of hoard gullet, perhaps, or something similar. Your HP and BAB are fairly low, unless you buff your con. -The_Mad_Linguist
Your power starts slow. Unlike even many Rogues, at level 1 you're stuck in back judiciously using your small number of level 1 and 0 spells while the front-liners get to feel continually special. (Even tier 5s and 6s can shine at level 1 and laugh at the Wizard. Then the Wizard levels and outshines them brighter than Daylight.) Hopefully you packed Cloudy Conjuration or some means of giving your spells some extra oomf. At best, you have 5 level 1 slots at level 1 from being a 20+ INT Focused Specialist. More likely, you'll have 3 or 4.
Managing until about level 5 when you can safely cast a spell or two every fight and not feel like you're wasting your resources is a challenge, if only to your patience. Things tend to get much easier from there, unless your DM is annoying and repeatedly targets your spellbook, imprisons you naked, sends Antimagic Field-generating creatures at you, or decides to "challenge" you by stripping you of your highest level spell slots on a whim.
Another problem is spell selection: There are often too many good spells for me to choose at a given level. What spells do I pick when my Conjurer hits level 3: Mirror Image and Glitterdust; Invisibility and Web; Rope Trick and Cloud of Bewilderment? Complete Arcane's Collegiate Wizard and Races of the Wild's Elven Generalist increase the number of free spells known, but these aren't always available or optimal.
Scrolls you want aren't guaranteed to be available on demand to pad your lean spellbook, but when you can Teleport across the world in minutes, your odds drastically improve. Cost is a significant factor unless your DM says you can use Secret Page to make spellbooks with every spell in the game at no charge, or you find another method. WotC assumes Wizards pay gold for their extra spells and don't use money tricks like spamming Water to Acid then selling the acid, or binding farms of Efreet for all the Wishes they want. (I'm not saying being a Wish farmer is necessarily a bad thing, but I am saying your DM is probably a reasonable person who disapproves of your trying to shortcut your way to divinity and ignoring his plot hooks. Your DM has feelings too, and he probably doesn't want to play alone.)
Sometimes, Wizard players become rampantly annoying when they ask their DMs what sorts of limits he puts on their power. "Can I use Shadow Miracle? Can I make a Simulacrum of a Solar to keep in my Bag of Holding? How soon can I turn this peaceful farming village into a hooker/terrorist/necromancer/ludicrously profitable encampment? What do you mean I can't cast the spells of my new Polymorph form? What's so bad about using Genesis to create a plane of pure gold/platinum/diamond/obdurium that only I can access with a hole in the middle big enough for my construct army to mine out?"
Playing a Wizard effectively requires preparation, planning, and the ability to anticipate your DM's actions out of character. Some people consider this cheating or unsporting, but if you weren't so smart out of character, why play a Wizard?
Also, your spell selection is largely at the DM's whim. If your DM prevents you from expanding your spellbook, you're effectively an INT-based Sorcerer with less spontanaeity, stuck in the less comfortable realm between low tier 1 and high tier 2. This is especially true if your DM forbids Elven Generalist, Domain Wizard, Collegiate Wizard, or other means of cheaply expanding your spellbook.
By comparison, if a typical Cleric or Druid loses access to a spell or domain, there's typically little problem since they know EVERY spell on their list. If the DM doesn't like Druids casting Flame Strike, it's no biggie; just Wild Shape and instead cast Flaming Sphere or Vortex of Teeth or Creeping Cold or... -Endarire
Pros: At every level, you have an "I-win" button. From the lowly "Power word: Pain" to the mighty shapechange, and anywhere in between, you rule supreme. Your spellcasting stat, intelligence, is optimal (with the exception of a hypothetical constitution-based spellcaster). You only really have one ability score to raise, so even in low point buy you aren't going to be less powerful - just slightly squishier.
A wide range of prestige class options are open to you, and the access to bonus feats makes it easier to qualify for them.
At first level, you possess the most fungible assets of any party member, as well as scribe scroll.
The single spell "Contact Other Plane" is so useful that it removes any downside for having prepared casting, and that's without truly abusing it.
With access to wish, time stop, genesis, and ice assassin, there is absolutely nothing that a Wizard20 cannot do. Scry&fry is a trivial example.
Basically, a wizard can learn any of the hundreds of spells that are broken in some circumstance or another. With divinations, you'll know which ones you'll need to prepare. -The_Mad_Linguist
One of the facets about wizards that I find the most broken is how much stronger he gets with a bit of forethought and prep-work.
So many spells are of Permanent or Instantaneous duration that can be used and abused to the point of ridiculousness (and can generally be accessed far, far sooner than would generally be expected). Spells like astral projection, clone, simulacrum, and explosive runes (yes, I prepared them this morning) can be used in ways to make yourself nigh invincible, and there's definitely a reason why the last one I mentioned has the initials E.R.
Unlike most other classes, who can generally only buffer themselves against most effects (such as improving their AC), wizards have access to so many spells that render them untouchable, with a bit of forethought. Simply telling someone, "no, you can't affect me 'cuz I'm 100% immune" is a sure way to survive an encounter with mundane and exotic critters alike. Protection from arrows, wind wall, ironguard, polymorph, mind blank, true seeing, protection from good/evil/law/chaos, protection from vermin, shapechange, and a whole host of other spells can render threats to entire campaign worlds null and void.
Wizards also have myriad ways of increasing their spellcasting prowess both inside and out of combat: ioun stones, metamagic rods, pearls of power, rods of absorption, staves, wands, scrolls, rings of wizardry, spell-storing weapons, and a slew of other items are specifically designed to do horrible things to a given game (and those are just in Core). That's not even including the in-game strategies a wizard has access to. And Reserve Feats.
Have I mentioned that even low-level spells can essentially take down encounters by themselves at near-epic levels? Properly utilized, even grease and silent image can render creatures of amazingly high CR down to mere trivialities to kill. I'm sure there's a way to do the same with prestidigitation, if someone really tried.
Heck, four 4th level wizards, properly equipped, could take down the tarrasque. Fly + Melf's acid arrow for the win. -Lycanthromancer
Being able to kill people with your mind makes for an excellent scenario akin to Revenge of the Nerds. As the saying goes, a high level Fighter can hit stuff really hard. A high level Wizard can remake existence in less than a round's time on his chosen plane. As another saying goes, "In mortality, the shortest way to divinity is through wizardry."
A level 15 Wizard worth his spells is effectively a demigod, able to turn X into Y, go where he pleases on this plane and that, blow stuff up because it doesn't belong there, give life to Simulacrums of his favorite dragons/outsiders, call his favorite deity via Contact Other Plane and get scooped on what spells to prepare for that time period, Clone himself a backup self, and enslave cities with Charm/Dominate >>all in the same day.<< (Really, a Wizard can access every spell if only indirectly. A Solar casts spells as a Cleric20. An Efreeti can emulate L6 Druid spells, and there's probably some extraplanar Archivist, Psion, Erudite, Artificer, <class name> who'd be willing to help you for a large enough bribe or a strong enough Charm/Dominate Monster. Gate one in and have a ball, or better yet, a Prismatic Sphere!)
If someone uses the phrase, "A Wizard did it!" you can choose to take credit without speaking a word.
A Wizard knows a lot. Potentially, he knows everything. More likely, he knows the relevant stats of any CR-appropriate fight and then some. A level 5 Wizard who boosts his INT and Knowledge checks could go to some random stranger, take 10, and tell them all their childhood secrets. Even the DM might be creeped out at that. -Endarire
Cleric:SpoilerCons: Often requires Divine Metamagic (Which is occasionally banned) and Nightsticks (may be banned or demoted to un-stackable). Needs to have some idea of domains chosen (although that's only at low levels).
Undead Creation is often Evil, and thus banned for Good clerics. This also extends to other aligned spells. Rebuking is considered much stronger than turning undead.
PrC'ing is a must. You really don't get anything by staying in Cleric.
Just because you're a cleric, people will be expecting you to heal. This is a trap. Healing in combat has proved to be not as optimal as other actions.
Feat heavy. Clerics usually require 3 feats (Extend spell, persist spell, and divine metamagic), and may require additional feats to qualify for PrC's.
You have an aura. Specifically, you are a giant neon sign to anyone who uses the Detect alignment spells. -Chaos Josh
Pros: Divine Metamagic: Persist is easily their best trick. The ability to make spells such as Divine Power, Righteous Wrath, Lesser Vigor, etc. etc. last all day is one of the best tricks for buffing and forgetting about it. This is especially useful for breaking the metamagic cap, and spontaneously using metamagic.
If you need skill points, Cloistered Cleric is the ACF for you. You'll gain 4 skill points/level, a form of bardic knowledge, additional spells and free use of the Knowledge Domain, while only losing on average 1 hp and medium armor profs (which is made up by some PrCs) (The loss of BAB is covered by Divine Power).
Clerics gain some of the best minion creation spells in the game. This includes the summon monster line, gate, planar ally, animate dead, etc. This is not including what a cleric may have by rebuking enemies, either.
Domain spells, and also the domain powers can be very helpful. This also makes a one level dip in cleric good for almost any build. You could potentially gain 2 feats AND the ability to use all cleric scrolls/wands/staves including those of your domain spells. Heck, having the Magic domain for a 1 level dip means you net wizard/sorcerer magic items as well. You can even pick up Trap Finding, Uncanny Dodge, or many other class features through this dip. And lets not forget that some even give you a +1-2 to caster level on certain spells, or even the ability to turn additional creatures. This isn't including the Divine Magician class feature in Complete mage, giving you any 9 wizard spells (1 per level) from specific schools.
Some devotion feats are strong, and are also powered by turning as well. These include using Travel devotion to move and full attack, animal devotions to gain flight/bonuses to Str, or additional hit/damage with Knowledge devotion. You get more devotion feats than the other classes as well. (potential of 3 as opposed to 2).
You have effectively ALL cleric spells on your spell list. You are not some sissy with a book that he needs to protect, or loaded to the brim with scrolls/wands like the artificer. This is an advantage whenever a PrC says something like "Able to cast seven different divination spells, one of which must be 3rd level or higher." or similar.
They get the very nice Divine Insight, which gives up to +15 insight to a single skill check (is discharged). This is powerful if you consider Knowledge devotion, and even without may replace the rogue (although going on that route may make the dungeon take more time).
You get Quicken spell. This doesn't seem that much better than the other tier 1's, until you realize that you can take Divine Metamagic: Quicken, breaking the metacap as well.
4 turning attempts are worth 7,500g. Hurrah for nightsticks.
You can buy a +4 to CL for 10 mins. for 20,000g. And it's Core as well.
Animate Dead Abuse: Combining Desecrate and animate dead could potentially net you a 10-headed Hydra zombie. At 5th level. Effectively a 75 hp tank with 10 attacks/round. Costs a bundle on Onyx though...
There's a lot of broken things you can do with clerics as well. Sure, everyone knows that Druids have wildshape, and wizards can create different planes, but do they have spiffy names like the Twice Betrayer of Shar or the Cheater of Mystra. The main broken thing, unlike the Planar Shepard or Incantrix, is that they rely on not prestige classes, but a feat. Initiate of Mystra allows you the ability to cast in antimagic fields. You can cast antimagic field. With Ocular Spell, you can persist antimagic fields. There's also Greater Compulsive Field abuse (Gain +2 str, 1d8 hp, and +1 CL by killing 1 commoner. Run through the town!).
There are so many GOOD cleric prestige classes. This adds to the variety of Cleric builds. Just going by the handbook here on BG's there is:
Ruby Knight Vindicator
Seeker of the Misty Isle
Borderline SAD. You only really need Wis, as it's the main casting stat. Every other stat could be a 10, but it's handy to have them higher. Not as SAD as say, Druids, due to lacking transformation skills (Without domain choices, however. A cleric with the transformation domain can persist a Polymorph at 9th level.)
The basic class is one of the best. Two good saves (being the important ones), a d8 HD, and 3/4 BAB are pretty good. The ability to cast regardless of armor, while also being proficient in it, is a sole feature of the Cleric in this tier (well, at lower levels anyhow). (For all it's worth, it's not important, but it is a pro).
Druid:SpoilerThe druid is a true powerhouse of a class due to the sheer versatility and power of its three main class features: wild shaping, spells, and animal companions. Able to function as a tank (or 2 tanks with wild shape and animal companion), summoner, battlefield controller, damage-dealer, scout (both with wildshape and with divinations), and healer, the druid is extremely flexible. -Akalsaris
Cons: - Most prestige classes are traps for the druid, as very few advance the things a druid cares about. Nature's Warrior, Master of Many Forms, and Blighter are all far weaker than straight druid. Planar Shephard is the only PrC that possibly surpasses straight druid, while Moonspeaker and Contemplative both give some things and take away some things.
- Very feat-tight. A druid gets 0 bonus feats and must take Natural Spell at 6th (don't argue this one), so every feat it takes must do a hell of a lot for the build, especially on a non-human. A summoner's feats are practically locked into Spell Focus (Conj), Ashbound/Greenbound, Augment Summoning, Natural Spell, Rapid Spell, and Elemental Summoning, for example.
- Spells are alignment-limited and the druid must have a neutral component to her alignment, which can limit the spell list sometimes, especially for summoning. Neutral (True Neutral) is easily the safest alignment in this regard, completely sidestepping the restrictions.
- Very few worthwhile alternative class features, unlike the wizard or cleric. The Shapeshift Druid is alright, but trades 2 good class features for one mediocre class feature. -Akalsaris
Pros: - The chassis: Druids have medium-high hitpoints, medium BAB, medium skills/level, medium-low armor and weapon proficiencies, and high fort/will saves. All decent, but not particularly strong, though the saves are quite nice.
- Spells: the most powerful tool in a druid's arsenal. First level starts off strong with Entangle, a very long-range battlefield control spell, and only gets better from there on. With a fast spell progression and wisdom based casting, the druid also has dozens of supplements' worth of spells to cherry-pick from, as she can cast any spell on her list with preparation. The ability to spontaneously cast Nature's Ally spells is another strong ability for summoning-focused druids, and can be helpful even to other kinds. Druid spells are typically either utility, battlefield control, or damaging, with a large sprinkling of divinations, healing, and buff spells. The Spell Compendium is notable for nerfing a lot of former druid staples, but introducing a ton of other excellent spells, especially self-buffs.
- Wild Shape: The next most powerful tool a druid has, at its best, wild shape allows a druid to cherry-pick through a dozen sourcebooks for animal forms that are the best answer to any given situation. Even if only limited to the Monster Manual, wild shape gives tremendous flexibility and allows druids of 8th level or higher to completely ignore Str and Dex in character creation, freeing up points for other stats. It also makes the druid's weak armor and weapon proficiencies a non-issue.
- Animal Companion: The linchpin to the druid's power, the animal companion is like having .5 more party members. At low levels it can function as a support tank, and at higher levels it can either be used to provide the party's less awesome members with flight, or it can become a tank in of itself. Dinosaurs especially are good at almost all levels. With 1 or 2 buffs such as a shared Bite of the Wereboar or an Animal Growth spell, the animal companion can easily match the party's fighter in tanking and damage output.
- Other class features: To top it off, the other druid abilities are pretty solid as well. Nature Sense is effectively a +2/+2 skills feat, while Wild Empathy is like a free, albeit limited, Diplomacy score. Venom Immunity is useful for evil druids who want to use poisons, while Timeless Body means that a druid starting at high levels can begin with +3 to all mental stats without the physical drawbacks. -Akalsaris
More cons for druids: doesn't (easily) get access to time stop and wish. At this tier it's a consideration. If you're playing gamebreaking characters, not having access to a couple of gamebreaking techniques is significant especially when a lowly sorcerer CAN get those tricks. -Rebel7284
Archivist:SpoilerCons: Dual stat casting*: This is a real disadvantage, meaning you can'T truly focus on one stat, since your spell DC's are based on your intel, and your bonus spells per day are based on your wisdom.
No domain access*: The domains are a great advantage, and the archivist does not, unfortunately, have access to them. At least, not without multiclassing. Domains are there for the spells, yes, but also for the domain powers!! Undeath grants extrat urning, planning grants extend spell, luck grants rerolls, travel grants freedom of movement, these are all awesome abilities.
No turn undead.* A staple of the divine spellcasters is their ability to channel turn undead attempts into divine metamagic. Unfortunately, you can't do that if you'Re an archivist, again, some prestige classes grant it, but then it means you get them later.
Basically, IMO, while the archivist is GREATLY versatile, way more than the cleric, he is someone lacking in other departments and this is why i have yet to play one (althought my next level 1 character might be an archivist...) -Alastar
Sacred exorcist, while being very good for the archivist, is not ideal for all campaigns, as it requires you to be good, as well as :''Only characters judged by their church to be examplary in faith and devotion, strong of will and upright in morality, are made exorcists''
I mean, it's not HARD to do, but maybe no everybody wants to be an exorcist/archivist.
*-See JaronK's pro section.
The time factor allows DMs to stop Archivists from actually getting the good spells if you don't have access to magic marts or a Warlock. Also, the fact that you're a divine spellcaster may make your party want you to be a healbot. If so, make sure to dip Sacred Exorcist, then persist Lesser Mass Vigor or Vigorous Circle, and tell them to shut up. -JaronK
Pros: Versatility: With his prayerbook giving him acccess to the whole armada of divine spells out there, the archivist, throught domains, prestige class lists, funky unearthed arcana spell lists and a slew of other things, can get virtually any spell he wants in his prayerbook, some of them at a lower level then a normal cleric!!! (I'm looking at you lesser restoration) This is a HUMONGOUS advantage in any game!!
Good skills, with a focus on intelligence, means an archivist can easily take knowledge devotion. This synergises well with his dark knowledge ability. The Dark Knowledge ability is a huge boon to the whole party. -Alastar
I have to say, Archivist dual statting is NOT a serious disadvantage. If you look at it, the only "dual stat" issue is that they use Wisdom for bonus spells. This would be annoying, except that they actually get one more spell at a given level than Wizards, so they've effectively got plenty of bonus spells anyway. Very handy. As such, they really don't need to boost wisdom much, though it helps.
Furthermore, while Archivists don't get domain abilities, they do get domain spells, which is often the important thing anyway.
And finally, Sacred Exorcist 1 is all you need for Turn Undead, so that's hardly an issue.
Archivists can cast almost any spell in existence, often at very low levels. Consider for a moment the Dragon Magic Favoured Soul variant that makes every 6th level and below Wizard/Sorc spell exist as a divine spell, and the divine Bard variant. In fact, I can't think of a single good Wizard/Sorc spell out there that isn't available to an Archivist (technically, you can actually get all Wizard/Sorc spells, but only because of the existance of a 3.0 PrC, the Hexer. But all the good ones can be gotten without 3.0 material). Furthermore, because the research rules allow you to research any spell that's a copy of an existing spell (without changing it at all) you can get all the spells you want, limited only by time. Or you can just have a Warlock make you some scrolls. Whatever floats your boat.
Also, a lot of spells were created with slow casting progressions in mind (Adept, Ranger, Paladin) and the Archivist can therefor get these spells much faster than intended... and with a Sacred Exorcist dip, you can then pull off stunts like Persistant Swift Haste (Ranger 2).
The Archivist even gets useful class features (namely Dark Knowledge). Because, you know, casting every divine spell ever just wasn't enough. -JaronK
Artificier:SpoilerCons: Really complicated. It needed the longest guide ever, just for regular game play ... see the Endymnion (sp?) threads. No CO-er ever made an easyplay or quickstart type guide, perhaps because you can't. -Awaken DM Golem
Pros: Artificers can, effectively, cast any spell in the game. The only thing remotely as broken as magic spells is magic items. And the artificer is really good at making and using magic items. -The_Mad_Linguist
TWF with Wands means, you are two Wizards, but it's expensive. You can torque Caelic off, by just suggesting Artificers CAN'T do something. -Awaken DM Golem
An optimised craftificer can make magic items ridiculously cheaply (as in at about 2.05 percent of the market price). Furthermore, using a Spell Clock that casts the spell that extracts Ambrosia(from BoED), Leadership, an item of continuous Wrack, and the item that turns pain to pleasure (BoVD), they can have continuously regenerating crafting XP. -Bastian
As I recall with Artificers, there's a spell that gives you an action point every round... and an ability to cast a spell off wand using an action point instead of a charge. The first spell is persistable. Go wand wielding maniac, go! And don't forget to get your wands off the trapsmith list, so that the level 3 limit isn't as much of an issue. -JaronK
Erudite Spell To Power option ONLY !!
(I'm stretching here ) Not many multiclassing options, not that you need them. You need a party Wizard / Mage Of The Arcane Order, to learn all those yummy spells from, but you get to play the Experience Is A River shuffle. Permanent weakness of the class, is the limited spell/powers choices on round 1, but just round 1 and you get Contigency. No Magic 9s until after Epic Spells ... umm, how's this a problem?
-Awaken DM Golem
Note that Erudite can also get access to Mental Pinnacle, which means he essentially doesn't need to know any of the powers in the spell's description and has unlimited power points without needing to spend feats on it (except the EK for Mental Pinnacle). Note also that while the spell costs a caster his spellcasting ability, the Erudite's manifesting ability would be untouched. -Agita
(Erudite Spell To Power option ONLY !!)
Elemental Envoy feat at 1st level, is almost as good as Leadership, but only up to level 6 ... so you dismiss it. Linked Power feat and Imprint Powerstones feat, get around the Powers per day limit well enough. Then you get arcane spells without V or S components. Pay the equivalent to 1 spell level, to eliminate M components; which is superior to Eschew Materials feat. And you get to be a spell point Wizard. Better than any early entry cheese, for Mystic Theurge type builds. UrPriest 2 / Psychic Theurge 7 is an option (yawn). Psionic / Magic translation problems produce spooky actions not at a distance (physics reference). -Awaken DM Golem
The current summarization does not do justice to the Spell-to-Power variant, as it leaves out their most powerful ability. I'm speaking of Arcane Fusion.
Why does this ability matter? Think of it this way; a Druid becomes pretty much all-powerful upon obtaining Natural Spell. Arcane Fusion is the Spell-to-Power variant Erudite's version of Natural Spell. Because the Erudite's power list is limited only by how willing you are to pay a 400 xp cost (that's for 9th level powers, lower level ones cost less), you can get nearly any spell from every class list.
Now, if having 9th level Psionic Powers, 8th level Arcane Spells, and 7th level Divine Spells isn't enough to justify taking this class to 20th, Arcane Fusion is. Obtainable somewhere around 9th or 11th level, turning Arcane Fusion into a Psionic Power allows you to manifest any 4th level or lower Psionic Power you know for the price of a single 5th level power. This bypasses your Unique Powers/day limit. Great Arcane Fusion does the same thing, but for 7th level and lower powers and at the cost of an 8th level power.
There is some gray area, such as Augmentations, but I'm not going to delve into that complicated mess.
Also, by RAW, an Erudite does not need to prepare his Unique Powers/day; he simply manifests them, and they stick. -Sinfire Titan