Glad to be of help on such a great project.
I think the closest parallel here for "things you can do all day" would be the Warlock. Making it a non-touch attack, or a melee attack etc might drop it down slightly in potency, and it's a good benchmark for potency.
There's a vague list here for reference:
http://dnd.kermodebear.org/InvocationLists
Beshadowed Blast: Lesser, 4th, Blast essence; Living creature struck makes Fort or blinded for 1 round.
Lesser is, at least in this E6 system, a singular, capstone ability.
Whilst this may correctly indicate that the E6 Warlock is dramatically subpar at the moment, if you want Lesser to be something you only get as a capstone in E6, then this indicates that a decent touch/+save is pretty decent.
Meanwhile, if it's something you can do ~ 3 times a day, then the comparison should be with a level 3 spell.
Keep in mind that my breaking point for balance is above the warlock. I aim for mid to high tier 3, while the warlock is considered tier 4. Being "more powerful than the warlock" is a good thing.
This is one of the reasons I like multiclassing. In hindsight, I think Ranks alone without it being based on level is fine - most classes with multiple hits to get full use out of it are at double cost / rank for it anyway.
Max bonus of +2 per class level is my preferred method, after thinking about it. This keeps it from being front-loaded (same bonus at level 1), but also allows a dedicated sawbones to turn it into a signature ability. If you're willing to optimize heal, you should reap the benefits. It does keep it from being a phenomenal dip for a combat class, but a +2 bonus to damage rolls and a few cool inventions may be worth it for some.
Inventions:
Knock Out Gas: If this is a "toxic", rather than "enchantment" ability, should this be a Fortitude save and have no effect on non-living creatures?
I want it to remain a Will save (think of it like Sleep), but I'm willing to include a clause that creatures that do not breathe are immune.
Unstable Elixir: Untyped damage?
Damn, another one. Should be acid.
Corrosive Acid (and several others): Splash Weapons typically have a Direct Damage component and an indirect component, see Alchemist's Fire, for example.
http://www.d20srd.org/srd/equipment/...alchemistsFire /
http://www.d20srd.org/srd/combat/spe...owSplashWeapon
As such, you may wish to account for this with these types of invention.
I'll look into it. It actually may be a good way to tone down some of the more egregious grenades - as I recall, Mangles basically called them "must-haves for every engineer," which means I'm doing something wrong.
Clockwork Decoy: Decay < typo. What size is the decoy? Stats? AC?
I'm thinking a construct version of the rat, which moves 20' in a random direction each turn, without being specifically commanded to do anything (it's a wind-up mouse).
I will add those statistics accordingly.
Automated Laboratory: This brings up an interesting question. How heavy are inventions?
They all emit a subtle anti-gravity field that exactly negates their weight. That or hammerspace. There's not going to be a real good answer for you on this, because I don't have one. You have to be generous with your suspension of disbelief to accept that the engineer can whip all this convoluted machinery up and carry it all around in like a backpack or something. Maybe an Engineer's Backpack should be an automatic invention at level one? It stores parts, powers inventions, and acts as a mobile workbench to construct them all.
Foothold Trap: At level 3, you have basically created this:
http://www.d20srd.org/srd/spells/glyphOfWarding.htm. With a caster level of 10.
Maybe it should be 1D6 damage per Engineer level, and again, amend the immobilisation (if it's a bear trap, maybe they can open it, if it's a foot-spiker, maybe something based on Caltrops?).
I cleaned up the immobilization language (stealing it shamelessly from the Web spell), added a way to get out of it, and reduced the damage somewhat.
Trapspringer: With this, a level 1 Engineer has subsumed the role of a level 10 Rogue.
Portable Locksmith: At level 3, the Engineer has a lesser "Knock" three times per day. He's sort of making a Rogue feel sad here.
The Engineer is a Trapfinder with Open Lock and Disable Device. Perhaps these should give competence bonuses to these abilities, rather than a 3x per day (more than usually is required) "disable whatever"?
I like the idea of a competence bonus. I'll consider it.
Steam Powered Gyroscope: Might this be better named Gyrocopter? I could be wrong but I didn't think Gyroscope was a flying device.
Yes... that would be fine.
Crackerjack Caltrops: Needs rewording; as written, they may be spread indefinitely until they affect five creatures.
Might I suggest these use the actual caltrops rules, but with perhaps a bonus to the attack roll? That would actually be a power up to compensate for having a limited number of them.
I will consider it.
Flash Grenade: Possibly this should be done in a similar way to the
Thunderstone, but with an additional DC to avoid blindness? Automatic blindness, even for a round, is the domain of a spell like Sunburst.
For a level 2 invention, you're right, it is a bit much. I've removed the dazing, and reduced the blinding.
Homing Rocket: So it's basically Magic Missile, cast at caster level 7 without a Shield spell equivalent or the ability to select a target? Perhaps this should deal 1D6 damage + 1D6 for every two Inventor levels?
I've reduced the damage to be a bit more in line with level 3, but did give it the ability to actually home in, ignoring concealment and partial cover.
Pocket Bombard: This is another automatic no-save-just-suck, but it's also competing favourably with Orb of X, which are level 4 spells in terms of damage output and effect.
Added a Reflex save. I stand by the damage, though.
Shrapnel Mine: As written, an Inventor can lay a Shrapnel Mine and come back days later. Again, this is a glyph of warding with bonus abilities and a much higher average damage.
Glyph of Warding isn't exactly great damage-wise, so I don't consider this too much of a problem. Added a limit to the duration, though.
Time Bomb: Caster level 8 Fireball, with extra features.
Fireball is not a very good spell. To me, saying that something is better than Fireball tends to be complimentary. Keep in mind that the engineer's inventions are a bit more powerful than spells because he has commensurately fewer of them, and he can only prepare any particular invention once.
Overall, I'm getting a very, very powerful vibe from the engineer. I'll probably have a closer look and see what a level 6 Engineer can feasibly pull off alongside another character.
Though I am reluctant to admit it, I can see some of the engineer inventions being a bit over the top. I will do my best to rectify the most egregious ones, while still maintaining the flavor and power of the class.
Table's out of date on the Poet; level 6 should be Full of Sounds and Fury.
Fixed.
For the Noble, would an initiator Archetype "War Marshal", with the focus on White Raven (and any other Leadership-brand manoeuvres, I don't keep up on homebrew Bo9S styles to keep track) be an idea? It's definitely within their remit as the Boss-man.
Will consider, though I'm trying to stray away from adding these kinds of archetypes to non-alternate class.