QUOTE (Karoline)
Bad Dr. Funkenstein. You know mistakes aren't tolerated here

Mistakes are fine. Adhering to them as law isn't so much.

Honestly, if I were designing an assassin built around an infiltration specialist, I'd go with a standard adept of the Silent Way who augments his abilities with technology. I'd start by maxing out my Agility as high as I could without it being too much of a BP burden, then focus on a decent Charisma and Intuition score. Strength should at least be 3 (giving you a 8P unarmed strike with the primary build below), Magic needs to be maxed out at 6, and Edge, Reaction and Willpower should all be solid, too. Honestly, this is the type of character that benefits from a heavy investment in Attributes, as you can benefit from every single one of them.
Skillwise you'll want to go with either Unarmed Combat (Martial Art) 6 or Unarmed Combat (Martial Art) 5 and Infiltration (Urban) 5 if your GM lets you split up skill groups. You'll want the Stealth group at 4 for sure, and Influence is a really handy one to have, too. But if you can't afford it, at least get a good Con score. You'll also want Hardware and whatever other skills are required for breaking-and-entering. Athletics is another group to consider picking up. Everything else is purely up to taste, really. Security Systems and Security Procedures are must-have Knowledge Skills, though.
As an adept, Improved Infiltration 3 is only 0.75 power points and, if you max your Magic attribute and avoid implants, Agility Boost 1 will net you about 2-3 points of Agility every time you need to use it with a negligable chance of drain. That's basically +5-6 dice to your Infiltration for a single power point. Throw in Improved Reflexes 2 with a geas limitation (if your GM is allowing that optional rule from
Street Magic) for 1.85 points, and you have 3.40 points leftover for anything else that tickles your fancy. Killing Hands, Critical Strike 6 and Distance Strike, if all geas limited, costs 3 points and gives your unarmed strikes a damage code of [(STR/2)+6]P that you can "shoot" at people, and you still have almost half a point leftover. Use that to score Improved Sense: Damper and Improved Sense: Thermosense and you're pretty damn set as an infiltrator-assassin already. The best part? You're totally undetectable except to Assensing, and a single grade of Initiation and the Masking metamagic will cover that up nicely. Alternatively you could go with Facial Sculpt and Voice Control for the ultimate master of disguise, but that's an entirely optional build path. Yet another option is to score Elemental Strike and choose an element that's quiet but halves Impact Armor to make your unarmed strikes all the more deadly. Most GMs will house rule it to work with Distant Strike, too, but you should ask before considering that option. It's still a good option either way.
With your basic skill set covered, you can then get started on technology to supplement and accentuate your talents.
Start by grabbing Contact Lenses 3 with Flare Compensation, Low-Light and Smartlink, some Glasses 4 with Ultrawideband Radar 4 (Radar Sensor 4), Vision Enhancement 3, and Vision Magnification, and a pair of Earplugs 3 with Audio Enhancement 3 and Select Sound Filter 3, and most of your sensory needs are already met. You can score some Microsensors disguised as buttons or whatever else you like on the cheap, and stack up on even more sensors such as MAD Scanners and Cyberware Scanners. Invest in a commlink with a Firewall and System rating of 6, then add in Nonstandard Wireless Link 6 and Hardening 6 to make it difficult to detect and highly resistant to jamming/hacking. If you have the cash, get a pocket Agent hacker to defend it for even better security.
Buy a set of Form-Fitting Body Armor instead of a Chameleon Suit and twink it out Thermal Dampening 6, Shock Frills (to accentuate your unarmed abilities and a great "quit grappling me" security measure), and Ruthenium Coating. Now you have the equivalence of a Chameleon Suit when you need it, but you can also wear it underneat your other costumes/armor, too, with a minimal chance of detection. Use Clothing to score the other big armor options such as Nonconductivity 6, Chemical Protection 6, and/or Fire Resistance 6 based on situations. Or, if you have the Body for it, just do it with whatever other armor pieces you fancy. Remember, even basic Clothing can support 6 points of modifications.
Just so you can take advantage of firearms, I'd get an Ares Light Fire 70 with the custom silencer accessory. It's one of the quietest guns in the game with a -5 penalty to Perception Tests to detect its firing. You can load it with Stick-n-Shock for most fights, or Subsonic rounds to make it even quieter (for a total of -7 or -9 penalty I believe). Some custom DMSO/Drug Capsule rounds are another option; when using those, you don't really care how much damage the base Capsule round does so much as you're using it as a drug delivery system. Lael and Narcojet are really nice options there. And, as soon as you can after character creation (or if you wanna blow a Restricted Gear slot for it), get the Ceramic/Plasteel Components 3 modification for the gun to make it the perfect stealth firearm, and maybe even Barrel Reduction if your GM doesn't have a problem with that on Light Pistols that use a silencer. That makes it as concealable as a Hold-Out Pistol. Since you have Distant Strike and a brutal Unarmed Combat attack, you can rely on that when you encounter the BigBadAss™ opponents in the game. This gun is for taking care of the little stuff and lulls enemies into a false sense of security when you let them "find" it on you during a pat-down.
Oh, and if you do decide to skip on the Capsule rounds, at least get some Slap Patches loaded with Lael. It's an awesome drug for any character that doesn't want to leave evidence they were there.
Next, grab a Maglock Passkey, Autopicker (or standard picks if you have a high Locksmith score), and Glass Cutter. Maybe even get the Body Cavity Escape Kit from
Arsenal if you don't mind having a tube shoved up your ass on a semi-regular basis. Multiple fake SINs and Licenses are great, too. You'll definitely want a Sequencer and Electronics tool kit if you have the appropriate skills for it, which you should as an infiltrator.
When you can afford it, look into Retinal Adjusters and Altskin nanoware. Combined with the Facial Sculpt/Voice Control optional build earlier, there's almost nothing that can keep you out with a little spy work ahead of time. See if you can talk your GM into allowing an external version of a Nanohive (which should certainly be possible; it's lame that they don't have rules for it) and you can pretty much have that nanoware available whenever you need it without causing you to be in the poor house... and all with zero impact on your Magic or Essence.
All that is where I'd start as an assassin-infiltrator. Sure, there's lots of cyberware that can get the job done, but this is one of the few fields where an adept actually excels. And there's tons of growth options, too. Traceless Walk, Improved [Stealth/Athletics/Unarmed/Influence skills of choice], Adept Centering, Attunement (Tools), etc. And if there is some situation where you have to appear as a regular Joe Schmoe, you can leave all the toys at home, deactivate all your powers, and throw Masking up and it'll be
rough figuring out that you're anything but one.