The Needle Rifle; a silent assassin's weapon, capable of killing a man in moments. It fires a sliver of pure, crystalized toxin.

The Needle Rifle: 1d10 R, Pen 0, Felling (1), Toxic (4), Accurate.

It'll be hard to kill much of anything with that. The average bloke has a Toughness Bonus of 3, which now means that a hit will only do anything on a 4 or above. A sturdy T-shirt is basically all it takes to get AP 1; any sort of Guard campaign will have the baddies sprinting around in AP 3 or 4. Heaven forbid you fight any kind of high TB critter. What am I missing, guys? How do I make this gun good compared to, say, a Sniper Rifle with Dum-Dum or Man-Stopper rounds?

 Accurate gives you +1d10 damage per degree of success if you aim, to a max of +2d10. This means you now are dealing 3d10. Felling ignores a point of unnatural toughness so helps against Orks, Nids and Chaos marines, and if even a single point gets past toughness and armour then they need to test Toughness at -40 or take 1d10 damage that cannot be reduced by any means. 
So yeah the ability to, if properly aimed, take out an Ork Nob in a single shot is pretty hench!

Kasatka said:

I had completely forgotten that Accurate does something other than make Aiming better. That's pretty tasty.

Yeah it was a much needed bonus, though personally i'd prefer 'sniper' style weapons to get double armour penetration after a full action aiming, represent finding weak points in an enemies defense and lining up a good shot, rather than this very MMO style ramping up of damage. It's a passable system for now but as more 40k Rp core books and supplements come out the whole thing is getting rather bloated.

Kasatka said:

I'm okay with ramping up damage, since it winds up being the same effect anyway, and it's the only way to actually allow you to oneshot people with sniper rifles (otherwise even a completely unarmoured politician with 5 HP can't be taken out with a single headshot). I think aiming at weak points is something that needs to be handled by (a) the called shot action and (b) more careful NPC design - far too many NPCs have the same armour on all locations.

 Don't forget you can apply different types of toxins according to some texts. So there are alternatives to just dealing an extra d10 damage.

Santiago said:

I'm pretty sure it can't be loaded with anything of the sort by RAW, though I'd allow it.

The GMs kit from DH did indeed specify several poisons, and stated that these could be used with needlers. It also gave the name of the "default" poison used as Tox-Jack, some nasty mix of chemicals and pollutants that were all readily available on most worlds in the 41st millennium.

@Darth Smeg & Plushy

Rogue Trader's Soul Reaver has some interesting new toxins as well.

Finally, don't forget that the number of degrees of success on an attack can replace the value on one of the dice rolled.

So if you got 7 degrees of success, but rolled a 2 on the damage, you actually got a 7, not a 2.

Its in the rules, look it up. Its probably in the top 10 of least known rules in the system, but quite effective with the Accurate weapons.

KommissarK said:

I remember reading this in the Black Crusade Rules but I didn't notice it in the OW rules. Could you point me to the page / paragraph?

Chapter VIII: Combat
Step 4: Attacker Determines Damage
Page 182, Second Paragraph
“For all attack rolls, count the Degrees of Success. The attacker
may choose to replace the result on a single Damage die with the
number of Degrees of Success from his attack roll. If the attack
inflicts more than one die of Damage, the attacker may replace
the result on one die of his choice with the Degrees of Success
from the attack roll. If a natural 10 is rolled on any Damage die,
there is a chance of Righteous Fury.”
 

KommissarK said:

You've got me intrigued now… What rules would you say round out the top ten?

CaptainTrek said:

Not sure if I could fill a top ten but there are often overlooked and forgotten rules:

Unsorted

• If you take more than one dose of a given drug within 24 hours you need to test toughness to see if it works and once it wears of willpower to not get addicted.
• DoS as a substitution for one damage die
• Weapons that were jammed need to be reloaded
• Amputated Limbs and infection
• Using the security skill to place traps
• Warp instability and Warp shock
• Rolling damage twice and adding against helpless targets
• Size affecting movement rates and stealth (also to hit modifiers but that is well known)
• Flak Armour providing 1 additional AP against Blasts
• GM / Group specific joker (yeah I couldn't come up with a 10th rule )

Musclewizard said:

That's a pretty solid list, actually. I can't think of much else.

Musclewizard said:

Huh, I thought it was concealment/stealth or demolitions to place traps. Learned something new.