So, we're planning on storming a building with magical support

With most of the group being mundane I'm looking for some gear/tactics to help us 'stealth' past any kind of defences, which i suspect will be patrolling mages and/or spirits

any thoughts people?

PS: we're styill using sr3 rules

Cheers

Do your homework. If you can get guard schedules, accounts for magical defense that give an idea of where and when you might encounter wards, optical networks, etc.

Go in somewhere unseen. As silly as it sounds, how many people will think to patrol air conditioning ducts, sewers, or other "dead spaces?"

Use distractions. Large crowds work well to hide auras, explosives draw more attention. You might want to consider making it a magical distraction by hiring a wiz-kid gang or something. Alternately, go in for a limited artillery strike: a remote-controlled mortar barrage of white phosphorous, say.

Passive defenses can be overcome by destroying the physical basis of the barrier - explosives, thermite, acid, plasteel-7 catalyst, old-fashioned sledgehammers, etc.

Magicians and adepts should be targetted first and hit hard with something damaging - flooding the building with neurostun gas and going in with chemsuits works well.

Spirits are just bad news. You can destroy them in melee combat, but if you're going up against heavy spirit activity, you need spirits or magicians of your own.

In a pinch, flood the building with FAB III Delta and let God sort 'em out.

Remote-controlled mortar rounds? Enough neurostun to flood a building? FAB III Delta?
This is a runner team, not a Firewatch squad!

Two things I used to great effect in a recent building infiltration was a high-rating jammer and signal amplifier (it's a bitch to coordinate a defense of a multi-floored building by word-of-mouth) and the Concealment power of a high-force spirit. Note that unlike Invisibility spells and mundane stealth techniques, I think Concealment shields you from astral detection, too.

Magic security counters magic threats, like projecting magicians, spirits, spells etc.

So it might be possibly that mundane runners can infiltrate a target with heavy magical security, where a magic wielding group would fail.

Theoretically .

Remote-controlled mortar rounds are actually a ridiculously easy way to pinpoint-deliver a lot of explosives without having to carry them around. I'm also a fan of the cheapass drone with the one-shot rocket (or missile) launcher on it.

Security always gets edgy when random shit happens, though... the whole "distraction" concept has some selling points, but I'd usually rather deal with the entire security force taking the "bored and sleepy" penalty.

Remember that stealth does work against astral searching.

Also remember that there are personnel who are supposed to be walking around that building. Likely there are too many for the mage to know them all. So disguises and the like are still very relevant, as long as you can keep your signature from showing you're scared out of your pants.

Make sure the GM realizes it won't be very fun if he uses the rules as printed and rapes you because there are so few mundane defenses against magic.

Mundane emergencies are great for distractions. The building across the street catches fire, everyone goes to watch it burn. Things like that, a car crash or accident. Just don't do it to the building you are infiltrating or Security will be on alert.