Hi everyone, I have one question about psyker and foreboding power.

If i got this right, psyker can use this power at any time he would preform evasion test, but he rolls -10 perception test.

I know that that Dark Heresy 1e had limit of 1 power per round, even if it is reaction, but in 2e i don't find that rule, so it means that psyker can use Foreboding 2 times per round instead of dodge (if he/she has step aside) and still cast a psyker power during his/her turn, am I right?

In the power's description stands: "Action: Reaction"

A player has one reaction per round, p.217. Does that clarify it for you?

I don't quite recall the "1 Power/Round" restriction from DH1, but a similar rule exists in DH2 as the "1 Concentration-subtype Action/Turn". As Reactions occur separate from a character's actual Turn, there are no conflicts with using Foreboding in the same Round as another power (unless that power is an Extended Action or something).

Concerning the interaction between Foreboding and Step Aside, since a character with Step Aside can make two Evasion tests and Foreboding can be used in place of an Evasion test, a character can use Foreboding twice by extension.

Asymptomatic is basically right. If I were you GM that would work. But if you have one who holds tight to the exact wording it might not be applicable, as it states either a dodge or parry...but this is a question of interpretation.

The concept of one power per turn stems from DH1's restriction of not being able to take the same Half Action twice in a turn. Thus you could only take one "Focus Power" Half Action each turn (this is also why there is such thing as a "Full Move" action, instead of just telling a character to make two "Half Move" actions, as well as a "Full Aim" action instead of just taking two "Half Aim" actions). This was enforced by the wording in DH1, page 188, under "Half Action" - "Note that you may not take the same Half Action twice." In theory this actually means you could perform a Focus Power Reaction and a Focus Power Half Action without restriction, but the reaction would occur outside the turn anyway. Further, you were functionally limited to only one Attack per turn in DH1, so you also couldn't Half Action Focus Power an attack, and then also perform a Standard Attack (DH1 Errata v3.0, page 9, top of page right column, states that Focus Power as a Half Action was functionally the same as a Standard Attack).

As mentioned above, DH2 has turned this restriction into only being on "Attack" and "Concentration" subtype Actions; while some parts of the Action write-up are copy-pasted across books, the "Note that you may not take the same Half Action twice" part has been removed. Essentially that restriction has been simplified. Instead now Psychic Attacks do have the Attack Subtype.

As far as Step Aside... interesting point, personally I'd go for it for the same reasons Asymptomatic makes; Foreboding is made in place of an Evasion Reaction, I'm assuming it doesn't have the Attack or Concentration subtypes, there is no true restriction on 1 power per turn, Step Aside lets you make a second Evasion. It all checks out as far as I can tell (I guess the only new info I'm bringing to the table is the proof as to where 1 power per turn came from - but given how it now works in DH2 the old DH1 style of thinking isn't needed).

I should point out, even if DH1's Half Action restriction were in place, Step Aside would still work with Foreboding. The restriction on only 1 power per turn was -only- for Half Action Focus Power Actions, not Full Round, Reaction, or Free action Focus Power Actions. Focus Power Actions were treated as the same as Standard Attacks for the purposes of Half Action restrictions, but it still wouldn't force Reaction level psychic powers to be limited to one per turn (they are after all, Reactions, not Half Actions, and thus not subject to the "cannot take the same Half Action twice" rule). Consider that this is how Force Weapons work in Dark Heresy. If you can't Standard Attack (Half Action) and Focus Power (Free Action - at least, I think it was, I don't have my IHB available to me, but I could swear it forced an actual "Focus Power" Free Action when it was used; looking at DH2 its a Half Action now, wonder if it was a Half Action in DH1 - I think that might of caused a bit of a rules conundrum back then (which it should given how things are), and thus yet another reason we have DH2) with a Force Weapon (to make use of the Force Weapon's most basic bonus purpose), well, that's just stupid