Does anyone spend category points to upgrade a tree?

[Orion]

And if so, which ones are worthwhile?

[Cadex]

Yes, but whether it's an optimal choice depends on several factors such as your build, playstyle, and the difficulty setting.

For some builds, one tree is crucial or heavily-used enough to be worth it. In other cases, there aren't any other trees worth unlocking, either because they just aren't useful to the build or you don't have the spare talent points to put in them.

I haven't played enough classes to make a list, but I'm sure there are many worthwhile examples. One of them, in my opinion, is the Stealth tree on a rogue. The extra category point will increase your odds of maintaining stealth toward the end of the game, which can make a big difference in damage output and survivability.

On the other hand, there are also plenty of trees where it would be wasteful to put a category point. Particularly those with talents where only the raw talent level is used for scaling or where additional effective levels have severe diminishing returns.

[grayswandir]

One in particular is Doomed's shadows tree, since upgrading it gives you a fourth shadow.

[jenx]

There are lots of talent trees worth investing an extra point in. In most cases, it is only worth doing with your final cat point, once you see what the difference makes with 5/5 talents. You can add it, then remove it and see the difference. But once you exit the level up dialog, it is there forever. So I often keep one spare for a few levels and wait to see the difference it makes once I have the talents I use at maxxed level.

If all it does is increase dmg, then don't do it. Use it instead if it increases range, duration, a key percentage (e.g. somethings goes from ~90% to over 100%, making them failsafe). On some trees, it makes a massive difference.

And in some trees, the extra point makes almost no difference.

[Mex]

I have yet to see a tree that is worth investing a category point in.

You can find mastery on items if you care so much for the extra shadow.

I would like to know what tree specifically you are talking about that benefits so much as to justify using up a precious category point.

[cttw]

Stealth tree with items, tricks of the trade and an extra cat point can be fun. The bonus to crit increases, and so does stealth.

[jenx]

I have yet to see a tree that is worth investing a category point in.

You can find mastery on items if you care so much for the extra shadow.

I would like to know what tree specifically you are talking about that benefits so much as to justify using up a precious category point.

There are lots of trees worth investing in. Solipsism, Ooze, Dream Hammer, Nightmare etc

[Mex]

You need to be a bit more specifics as to what benefits this gives jenx.

If it's simply even a 10% increase in damage then it's not worth it.

[Tom]

It may be silly but I can not play a thief without RUSH.
Maybe I would be better off with rushing boots, but they do not grow on trees and they might have a short attack distance.
So I invest in that tree only for RUSH

[jenx]

I did above. You boost a tree when it gives extra range, extra duration, extra percentages, but not when it just gives extra dmg. The trees I listed, and there are many many more, all boost either range duration or percentages of very important talents. For example, giving anything summoned an extra turn can make a big difference (e.g. bloated oozes), or giving dismissal a boost in percentage chance (and the whole solipsism tree in fact) is desirable for some builds.

[Mex]

If you're going to make a claim at least present the facts in a specific manner.

Here is an album with pictures comparing each tree's abilities you mentioned and the benefits a category point provides:

http://imgur.com/a/kpEcX#0

NOTE: Where it says "improves with mindpower", please think in terms of percentage increase.

Nightmare

Nightmare: Damage increases by 6%.
Night Terror: Resistance penetration from 32% to 33%, Night Terror 12 to 13 turns.
Waking Nightmare: Damage increases by 6%, Chance to blind/stun/confusion from 33% to 35%.
Inner Demons: Increase turns from 14 to 15, 19% to 20% chance for demon to be summoned.

Comments: Really not seeing any meaningful benefit here, moving on.

Ooze

Mitosis: HP of ooze increases by 6%. 33% to 35% all damage resistance.
Reabsorb: Increases mana burn damage by 6%.
Call of the Ooze: HP of ooze increases by 8%. Melee attack through ooze increases from 195% to 204%.
Indiscernible Anatomy: Enemy multiple crit modifier decreases from 60% to 67%. Resistance to disease/poison/wounds/blindness form 75% to 78%.

Comments: The HP increases a little bit I suppose, but by a laughable amount. Again, not really much to see here.

Dream Hammer

Dream Smith's Hammer: 219% to 225% weapon damage. Base Power increases by 4%. Accuracy increases by 14%, APR from 10 to 11, physical crit from 10 to 11 (10% increase).
Hammer Toss: Increases damage from 157% to 161%. Accuracy of Dream Hammer from 65 to 75 (14%).
Dream Crusher: Increases damage from 157% to 161%. Increases Dream hammer from 65 to 75 physical power (14%). All Dream Hammer from 57% to 61%.
Forge Echoes: Increase damage from 157% to 161%. Adds 6% more damage to burning.

Comments: Again, very minimal benefits, the only "significant" % increases are fairly irrelevant.

Solipsism

Solipsism: Convert damage from 56% to 60% into psi, 56% to 60% heal regens psi. Reduce psi damage from 46.4% to 47.2%.
Balance: 75% to 85% of mental save substitutes others.
Clarity: Increase global speed by 4% effectively.
Dismissal: 68% to 74% of mental rolled against damage.

Comments: Again very minimal benefits, the mental save doesn't even go beyond 100% and the Dismissal really doesn't improve significantly.

"increases range, duration, a key percentage (e.g. somethings goes from ~90% to over 100%, making them failsafe)"

1. No abilities improve in range for the ones mentioned and even if they did an increase in 1 range is insignificant
2. Duration increases only in Nightmare and by 1 turn, again insignificant.
3. Key percentages do not go above 100% and always gain marginal benefits.

Please provide some evidence before making such claims, it is fairly clear that a category point in an already unlocked tree is a very bad decision and even if you were focusing on that tree (I don't see why you would) the benefits are really pathetic and a waste of time.

[jaumito]

I've heard that spending a category point on Stone Alchemy lets you extract unobtainium gems.

[donkatsu]

There is no tree that's worth upgrading at the loss of an inscription slot. So, you would only spend a category point to upgrade a tree if your class has less than two useful locked categories. In the past, this would be the case for a handful of neglected classes who either had useless locked categories or no locked categories at all, and escort trees weren't as good as they are now, with the exception of Light.

These days, there are almost always at least two trees somewhere that you can splash points into for a reasonably good effect rather than the miniscule increase from upgrades. The only upgrade benefit that can compete is Cursed/Shadows. For that, relying on mastery from items is not a valid alternative unless you actually find said items.

[HousePet]

I'd be tempted to increase Solipsism with those numbers.

[Wolls]

I can't say it is recommended but honestly I like to throw the last Cat point into the Racial. It depends on the build but its usually fairly tight on the generic side so one Cat has more value rather then a Skill tree. For example as a Halfling you can get an extra turn out of Duck/Dodge and Indomitable plus the bonus to Luck of the Little Folk and Militant Mind. 1-2-5-3 with the Cat point.