A kind of noobish question, but what exactly does it mean?
For example:
Oleron´s Fervor, 10 % Chance for 200 % to All Damage
Does it mean that, if I have 2000 % Bleeding Damage, I get a modificator of 2200 % to this hit? And all other damage types I do with this hit (Pierce, Physical, etc…) will also get this modificator (+ 200 %)?
Or something completely different?
Yes, “all damage” will improve all damage types, think of it as of sum of "increased physical damage, increased fire damage, increased bleed damage, etc.)
Thank you. 
Flat Damage is also increased?
Why I ask this:
My toon is a One-Pony-Trick-Bleeding Trickster. And I try to solve which Augment is better: Oleron´s Fervor or Bloodscale Powder
Flat damage is the ONLY thing that get increased, actually.
Your skills/attacks just deal “flat damage”, and it gets increased by “increased damage”. If an item has a bonus to flat damage, it will be just added to your default attack and all skills that use “Weapon Damage” (scaled accordingly).
Okay…you lost me…
Can you give me an example how to calculate it?
Is +40 % Bleeding Damage every hit better, worse, equal as +150 % to All Damage every 10th Hit?
I would go with Oleron’s Fervor. Damage over time builds benefit from having temporary, large boosts to their damage more than other builds (applying a bleed with extra damage will keep that extra damage ticking until it wears off), plus you get a bleed damage bonus on that item anyway.
The only reason I’d choose the other is if you need a bit of health to round out your defensive numbers. The pierce resistance on OF probably won’t affect much since you’ll most likely cap that other ways.
If you use direct damage (physical, fire, acid, etc), then +20% damage and 10% chance for +200% damage are the same.
However, if you use DoT damage (trauma, burn, bleed, poison, etc), especially with greatly increased duration, then 10% chance for +200% damage can be much stronger, than mere +20% damage - because DoTs dont stack, and the strongest application from the same source takes effect.
Thank you, to both of you.
Will see; HP are good at the moment, no need to change augmentations.