Making a Serial Killer - Continued

[SpicyBoi_Nezu]

A while back, I made a post talking about how I would like to play as a serial killer in an upcoming campaign, and now that my character has died, I might actually be able to play said serial killer.

There was someone who said
So I'll go ahead and be the one to say the obvious with halfling rogue/ assassin/ black dog. A swift blade in the dark is hard to beat for a good murderer. Get an assassin's dagger and some murderer's gloves, pick ability focus and watch 'em drop like stones.

Slink off when nobody's looking, pick a likely victim, desecrate the corpse in a creative, calling-card esque kind of way and you're good to go. House Ghallanda makes pulling a Sweeney Todd an obvious choice.
And I need someone who might be able to give me a more in-depth breakdown of the level progression, as well as a few preferred feats. I have played a rogue before, but he didn't survive past level 3, so I really haven't actually played a rogue for more than 4 sessions, therefore I'm a bit lost on how to "Sneaky Boi"

[The Viscount]

Because Black dog requires the Least Dragonmark (Mark of Hospitality), which means you must be a Halfling. Rogue is the natural choice for all the skills, and sneak attack is useful here. If you're dying to enter earlier than level 5 it will take some doing. Provided your DM doesn't ban the technically cross-setting Strongheart Halfling (or allows flaws), you can take your least dragonmark at 1, favored at 1, and primary contact at 3. This will give you one extra skill point to use for Hide. Provided that your DM is amenable to the interpretation that this feat represents a permanent elevated cap and not just for the level you take it, this means you can do Rogue 4/Black Dog 5/Assassin X. There is a little redundancy in Black Dog and Assassin both giving a sort of HiPS, but there are theoretical situations in which one but not the other condition is satisfied.

In a normal entry of Rogue 5, I'd recommend entering Assassin first, and then Black Dog whenever you want. Assassin gives more utility in the form of spells, including ones to let you make easier sneak attacks and death attacks. Black dog makes a better poisoner. It's a matter of what you want to focus on. Whenever I'm using rogue to enter things, I always sit down and ask myself if I wouldn't be happier with Psychic Rogue. (http://archive.wizards.com/default.asp?x=dnd/psm/20040723b) The upsides are psionics for greater utility and sneaking. The downsides are fewer skill points and lack of access to the piles of rogue ACFs.

On the subject of ACFs, there is one you should consider for rogue.
Lightbringer Penetrating Strike trades trapsense for the ability to deal half SA to targets you ordinarily could not sneak attack so long as you flank them. Important since you need sneak attack to make a death attack. Easiest trade there is.

On the subject of feats, Craven is a common suggestion for extra damage. Staggering strike is the one that I'd really recommend for the ruinous effect it has in limiting enemy's action economy.

I'll mention Avenging Executioner if you wanted to go the 80's slasher route inspiring fear in your targets, if you were sill looking for alternatives.

[Bromley20]

Rogue 5, Assassin 10, Black Dog 5 is a solid build. The build is good for poisoning unsuspecting targets as well as stabbing people in the streets. I'm not sure what you want to focus on there so I'll just give recommendations for both.

Since you mentioned Black Dog prc, I'm assuming that you either want the poison abilities from the class or are just doing it for stacking levels to improve Death Attack. If you do want to use poisons, Master of Poison (DotU) may help by making poison application faster. If you want a cheap way to get poisons, ask your DM about using the Wild Cohort feat to get yourself an animal that has a natural poison and training it to provide its poison. I would recommend either Swindlespitter (MM3) if you want blinding poisons or Fleshraker (MM3) if you want dex damage. The Venomous Strike feat (DotU) will increase the DC of your poisoned weapons. The Assassination property (web (http://archive.wizards.com/default.asp?x=dnd/we/20070314a)) can boost the poison DC a bit if you dump money into your weapon. Check out the Poison Handbook (http://minmaxforum.com/index.php?topic=2714.0) for more info on poison use and specific selections.

If you just want to improve the Death Attack ability, Ability Focus will improve the DC slightly. A few items like the Assassin's dagger and Bracers of Murder (DotU) will boost the DC a bit while giving other benefits. If you can debuff the target with a status like sickened or shaken, you increase the chance of the Death Attack succeeding. Sickening Strike and Terrifying Strike (DotU) can reduce the target's save by triggering those statuses for reduced Sneak Attack damage. Atramen Oil (PH) can help even more by reducing the target's Fort saves. Mortifying Attack (CoR) can make everyone around you shaken and possibly lose their Dex to AC which means easier clean up with sneak attack. If you want to improve your Sneak Attack capabilities as a back up to your Death Attack, Wand of Golemstrike/Gravestrike/Vinestrike will allow you to sneak attack a specific creature type that is normally immune. Craven (CoR) is also very nice.

Based on the quote provided, it seems like you are leaning toward sneaking around and looking like you aren't a threat. If your DM allows skill tricks, Quick Draw feat and Hidden Blade skill trick (CS) will allow you to catch your target with their guard down and trigger sneak attack easier. Mosquito's Bite skill trick (CS) can make an enemy think you missed when you actually hit. Ask your DM about what happens with targets that are unaware of your presence. They may allow you to get a free attack in without the target noticing for a round. If they allow the free undetected attack, you can combine a poison and Sickening Strike to lower the target's save before delivering the Death Attack the next round. Hidden spaces (CS) can get you pockets to store your weapon, lock picks, or poisons without drawing too much attention. If you want to sneak up on targets easier, Darkstalker (LoM) will allow you to hide from annoying abilities and flank a few enemies who are normally immune (may not come up often). Ring of the Darkhidden (MiC) will allow you to sneak up on targets with darkvision in certain situations.

Sorry I don't have a level by level breakdown for you. I'm not quite sure what you want to focus on so I tried to stay vague enough for you to pick a style, while still giving useful info for the style.