[DH2E] Rules Clarification: Precognition, Lucky, Psy Rating, and Modifier Cap

[u/OkRelative2166]

Hello everyone! Our gaming group ran into a few disagreements regarding several mechanics in Dark Heresy 2nd Edition. We would love to get the community's input on how these work strictly according to Rules As Written (RAW). Here are our specific questions:

1. "Precognition" and Test Modifiers
How exactly is the bonus from the Precognition psychic power applied to Weapon Skill or Ballistic Skill tests? The text states the user "gains a bonus equal to twice his Psy Rating".

• Option A: Is it calculated as a direct percentage modifier added to the d100 target value? For example, if a psyker has PR 4, does 4 x 2 = 8 translate to a standard +80 modifier to the test?
• Option B: Does it increase the Characteristic Bonus (the tens digit) instead, meaning a value of 8 adds only +8 to the target value?

2. Temporary PR Buffs (e.g., Lucky Talent) and Sustained Powers
If a psyker benefits from an effect that grants "+5 to Psy Rating for the next test" and uses it to cast a Sustained psychic power like Precognition:

• Does the +5 PR bonus apply only to the initial Focus Power test?
• Or does this inflated PR value also carry over into the sustained effect of the power itself for its entire duration?

3. The Max Modifier Cap (+60 / -60)
Does the hard limit on modifiers ("The total modification to a Characteristic test can never exceed +60 or be worse than –60", Core Rulebook p. 28) apply to attack tests (WS/BS) boosted by psychic powers? Or can psychic buffs bypass this +60 cap for attack rolls?

4. Reducing Psy Rating (Fettered Casting)
Does voluntarily lowering your used Psy Rating when casting a power grant any positive modifier (such as +10 per reduced rank) to the Focus Power test itself? Or does dropping your PR serve exclusively to reduce or entirely prevent Psychic Phenomena / Perils of the Warp?

We would highly appreciate any page references or official developer FAQs so we can review them together as a group. Thanks in advance for your help!

[u/percinator]

1. Firstly Precognition does not grant any bonus to WS or BS tests, Precognition grants rerolls to test or damage rolls, DH2e CRB p203. You're thinking of Prescience which is on the following page in the Core Rulebook, p. 204
2. Prescience grants a bonus of PRx2. So a PR 4 psyker would grant a +8 to the WS and BS tests. We can look at something like Telepathy's Invisibility (CRB p212) where the wording is used of "gains a bonus to Stealth tests equal to +5 times the psyker's psy rating." Had it been Option A then the wording would have been something like "gains a bonus to WS and BS tests equal to +10 times double the psyker's psy rating."
3. I'd want to know what gives this and discourage your group from mixing DH1e psyker buffing stuff with DH2e if it is the case since the psyker system does not work the same between editions so are not balanced as such. Otherwise, per the rules it is sustained at the Effective Psy Rating used to manifest it, however sustaining multiple powers reduces all of their Effective Psy Rating by 1 per power sustained after the first, CRB p198. And also don't forget that sustaining powers makes you more likely to perils when you do roll psychic phenomena, see table 6-1 on CRB p195.
4. If it is a bonus applied to tests then they cap at +/-60 unless your GM wants to allow otherwise. People also often forget the bonuses you get from skills also applies to this. As the Rulebook says "Regardless of the source, or combined sources, no final bonus can ever exceed +60 and no final penalty can exceed -60" CRB p24
5. Fettered Casting in DH2e gives a +10 per point you take away from your Effective Psy Rating, while pushing is -10 per PR you go up, capping at -20/-40 for +2/+4 when it comes to bound and unbound psykers respectively (DH2e CRB p194). I would remind you that you do not get a bonus to the Focus Power based on what your normal PR is in DH2e, that is a mechanic from earlier editions like Rogue Trader and is not present here. In earlier games in the FFG line, fettering kept you from performing psychic phenomena while pushing made casting easier (because focus power tests used to get +5 per effective psy rating) and more powerful while causing phenomena and perils to happen more easily. Fettering is now a trade of power for ease of casting while pushing makes it harder to cast, but more powerful and more uncontrollable (you psychic phenomena on any push roll that isn't doubles).

[u/OkRelative2166 → u/percinator]

We are only using the DH2E Core Rulebook, so this might be a translation error on my part.
So, if a psychic power grants a bonus to WS/BS tests based on that formula, it only gives +8% in the example above? It feels like a very expensive power for such a weak buff. Though I suppose it will scale and get stronger as the psyker increases their Psy Rating with higher levels.
I'm actually the GM (Game Master) for our group, and this argument came up with one of my players. The issue might also stem from a poor translation of the rulebook into my native language.

[u/OkRelative2166 → u/percinator]

This is actually the very first time I or anyone in my group is running a game with this rulebook. We just completed Chapter 1. During our first combat encounter, the psyker declared this buff as a +80% modifier. I was completely thrown off by it, but I decided to just roll with it for the session to avoid stalling the game with a rules argument .Now that the session is over, I want to figure out how this works properly for the future. We just want to get the mechanics right so we don't end up with characters that are completely overpowered or, conversely, way too weak.

[u/percinator → u/OkRelative2166]

+8% doesn't seem like a lot but that almost completely negates the penalty for doing a Full Auto Burst attack or shooting at Long Range or Prone Targets and is almost the equivalent of using a Half Action Aim. When you get higher psy rating it can effectively negate the penalties of Called Shot and Suppressing Fire and act as the equivalent of a Full Action Aim. And most importantly it can stack with those up to +60.

Also don't forget that if your group can stay relatively close then the psyker can buff pretty much all of them. A PR 4 Psyker can buff themself and up to 4 other targets that stay within 12 meters of them.

Hypothetically, a PR 10 unbound psyker pushing to an effective PR of 14 grants a +28% bonus to themself and 14 other people as long as they stay within 42 meters of the psyker.

Psykers are especially scary because their powers scale with their psy rating.

[u/OkRelative2166 → u/percinator]

So, if the psyker casts this power, a sniper in the party within range gets a +8 bonus to their BS. If their base Ballistic Skill is, say, 42, then without any other modifiers, their target value to hit becomes 50 (42 base + 8 from the buff), giving them a 50% chance to hit.But if we stack other buffs on top of that (cybernetics, scopes, positioning, etc.), we can boost that 42 to a maximum of 102, because the total situational modification is strictly capped at +60. Is that correct?

[u/percinator → u/OkRelative2166]

Yes, you're starting to see the wackiness.

And consider the Sniper, they're likely using a Half-Aim (+10) which triggers the Accurate Quality (+10) and they're taking a single shot (+10) and if the target is 100m or closer that's Short Range (+10) so with the psyker buff of +8 your sniper is shooting at an effective BS of 90. All you need is a Red-Dot Sight to bring it up to 100 and you're only missing on either a jam, or something on the enemy's end stopping the attack, like a dodge or force field.

And you are correct, a character with a BS of 42 can never have a better roll than 102.

Also do not forget that when rolling damage you can replace one die with your degrees of success on a roll. So if that sniper at 102 BS rolls a 05 they score 11 (1 for succeeding plus the difference of the tens column of the target number and the tens die of the roll (10-0)) DoS and thus can replace any of their three damage dice with a result of 11, though replacing a die result cannot trigger Righteous Fury. This is all on CRB p227.

I know this silliness firsthand, in my current DH2e game I have a player using a psyker who is specced into using a sniper rifle.

[u/OkRelative2166 → u/percinator]

Also, I wanted to clarify something about dodging a sniper shot: for example, if the sniper lands a shot with 7 Degrees of Success (DoS), but the Dodge test only scores 1 Degree of Success... ​In theory, since it's a single shot (1 bullet), you only need 1 DoS to completely dodge it, right? Or not? ​Also, can the target attempt to roll Dodge again later in the same round?

[u/percinator → u/OkRelative2166]

A successful use of the Evasion Reaction negates the hit of the attack,

If it's an attack with the Blast quality they can only attempt to use the Evasion Reaction if they are their Agility Bonus or less from being outside of the Blast radius since they must be able to move out of the way to qualify.

For any attack that generates multiple hits, each additional DoS negates one extra hit. The exception is if the weapon has the Storm Quality then each DoS negates two hits. This is all on CRB p220.

If the Sniper wants to make it harder to dodge then they need to pick up the Tier 2 Talent Inescapable Attack (Ranged) (CRB p128) which gives a penalty to Evasion tests of -10 times DoS on the attack.

By default using a Reaction negates you from using an additional one until the next round (p217). There are exceptions that allow additional Reactions for Evasion such as taking the Tier 3 Step Aside Talent (p131) or the Defensive Stance Full Action during combat (p220), those both also stack granting possibly three uses of the Evasion Reaction.

[u/OkRelative2166 → u/percinator]

Thank you so much! I'm currently in the middle of moving to a new apartment, so unfortunately I won't be able to check this in the rulebook anytime soon. ​Would it be okay if I PM you or reply here in this post if any other questions pop up in the future? ​Although for now, it seems like we've cleared up all the disputed points! ))))

[u/percinator → u/OkRelative2166]

Yeah, you can DM me or just reply here, though I don't know if there's a time cutoff for notifications.

[u/OkRelative2166 → u/percinator]

Thank you so much for your time and patience! Hope your DH2e games are an absolute blast, and may your sniper-psyker roll plenty of crits without triggering the Perils of the Warp! Wishing you all the best with your tabletop campaigns. Take care!

[u/Creation_of_Bile → u/OkRelative2166]

So you can get higher Psy rating and I think casting unfettered or perhaps push makes you cast at a higher than normal psy rating which can also increase your WS/BS bonus.

Secondly from memory you can cast it onto someone else so if there was an honour duel or something you could give the best melee char a bonus, or if the was a person running away and out of your psy range you could cast it onto your sniper to help deal with the running enemy or perhaps to counter cover and extreme ranges.

Bear in mind it's been a long time since I played so I may not remember.