STR increases the crit multiplier for anything that can crit, which is most things aside from damage over time. It's generally best for embermages to stick with focus until late in the game when they can obtain larger bonuses to STR and DEX from items and enchants.

Originally posted by SchandFleck:

Im new to the game and tried a little bit.
I got stuck to the Embermage with the thunder skill tree.
Now Im courious about the stats.
Is it worth to spend points in strength? Because many skills have % weapon damage?
Does it also increase magic crit damage or only physical?

You could build Strength, Focus, or Both since Embermages are encouraged to use Wands and Staves that only use Elemental Damage hence utilize both Stats.
It's flexible. As Adec_Inc mentioned; it'll provide more damage by focusing on one Stat and Focus is favored on an Embermage. Boris the Stat Enchanter will take care of the rest.

Ok thanks for the answers!
I will focus on focus then.
Sad that there is no respec, because i like trying.

Originally posted by SchandFleck:

Ok thanks for the answers!
I will focus on focus then.
Sad that there is no respec, because i like trying.

You're welcome!
With TL2's post-game - highest leveled items will yield 30 (or 70 if powerful) per random Stat received from Boris up till 3 times.
At that point - 495 points invested directly from the Stat Panel will be a foundation to randomly customize the Stat spread from Enchants.
And using a high damage weapon at post-game levels will benefit the Weapon Damage being additionally sourced from these skills.
Hence it's not the end for mixing Strength and Weapons into the Focus-build late-game.

Further information:
The most useful spells for most embermage builds are Prismatic Bolt (main damage) and Ice Prison, which at level 15 becomes the most damaging nuke in the game (when recast is reduced to 2 seconds from like 10). These skills do not benefit from weapon damage, only Focus, elemental damage%+, critical, and critical multiplier.

Most higher level embermages will use Whorlbarb Skulls (+10 critical chance) and Rambren Skulls (+60% Critical Bonus, caps at 500%) on their weapons (usually Netherrealm Axe x1 or x2) to bring up their critical rate and bonus. I second what others have said - it is good for an embermage to put all of their skill points into Focus, and everything else can be made up with gear.

One last thing:
From Borris (stat enchanter), level 105 items can have at most +72 of one stat per enchant and level 99 items can have at most +68 of one stat per enchant. You aren't going to fill your items with stats that high, but it is good to know the exact limits.

*EDIT*
Fixed an error; It's "Ice Prison" not Ice Wall.

It should be further noted that Prismatic Bolt does very little without support from Fire, Ice, and Lightning Brand passives. In fact, PB can be safely kept at level 1 for reduced mana cost. This makes it a fantastic starter skill regardless of what you end up doing later.

I was under the impression that Prismatic Bolt got a lot better with higher Focus. The brands can only affect a single enemy per proc, which has a 2 second cooldown. If you're relying on brands (which are good, just not your main damage), you're only killing three guys every two seconds.

*EDIT*
Just did some checking on my best level 100 Embermage. The Prismatic Bolts seem to be doing around 20k, 40k, or 60k on the target dummy (Imperial Camp NG+5), while the brands are doing about 300-400k each. 100% Critical rate and ~420% Crit bonus. All mentioned skills are 15. Focus is about 1500.

The brands definitely deal huge damage, especially if you're attacking a single target, but the Prismatic Bolts are still doing a ton, they attack much much faster, and they are the key to killing big groups, along with Thunder Locus. For comparison, nothing comes close to the 2,900,000 damage I've gotten from a single Ice Prison for bosses.

Focus helps as much as it does any spell, but the base values on PB are low, and mostly increase from character levels rather than skill ranks. IIRC they also have very low crit rate compared to Brands.

1500 focus is beyond endgame territory, and 60k damage output isn't exactly jaw-dropping for that amount of investment. There are better aoes like Hailstorm, faster DPS spells like Frost Wave, and heavier hitters like Shocking Orb. PB is a top tier starter skill, and it can carry you the rest of the game if you wish, but it's far from the pinnacle of embermage spells.

I am fond of Thunder Locus as well, for what it's worth. A great tertiary skill, to be sure.

It's important to note that, out of all of the spells mentioned in this thread, the only one that uses Weapon DPS instead of Focus is Shocking Orb. None of the others will benefit from strength beyond the Crit multiplier, which you can get much easier with Rambren Skulls.

Originally posted by SchandFleck:

... ... ...
I got stuck to the Embermage with the thunder skill tree.
... ... ...
Is it worth to spend points in strength? Because many skills have % weapon damage? ... ... ...

Originally posted by Cannonaire:

It's important to note that, out of all of the spells mentioned in this thread, the only one that uses Weapon DPS instead of Focus is Shocking Orb. None of the others will benefit from strength beyond the Crit multiplier, which you can get much easier with Rambren Skulls.

True - although if the original question was asking about the Thunder Skills overall then I'll add these DPS mentions on topic (although I admit these are less popular choices):

Shocking Burst = (limited range)
Arc Beam = (weapon restricted)
Shock Bolts = (random direction)

This "Shocking Orbs, Dps, Embermage" Guide does split the investment between Strength and Focus hence it seems that Focus is favored in every scenario for Embermages:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=924384705

Based on personal experience, yes.
Building Embermage with Thunder skills tree are very difficult and I'm stuck with it.

I'm even like challenge myself with: "Try to beat torchlight 2 with Embermage with Thunder skills tree but with other character skills only took certain passive."

I'm playing it with mod of course because level restriction in the games (you must reach certain level to unlock certain skill you want)
Even I must find wand that have electric elements and use dual wand to it, because if spend on Thunder skills tree but equipping ice, fire or poison elements feels like doesn't match or doesn't make sense at all. Including only take active and passive skills on all Embermage thunder skills but also took the Embermage skill for healing (represent with skull wearing hood lookalike surround with scary red aura).