Having the opposition be a single individual bloody sociopath who can engage a shadoowrun team as a sane action gives me a lot too work with in your scenario. I am just going by the fact he is driven, fights Shadowrunners, ruthless, skilled, experienced, and wants the Run team dead. Let's call him Dexter.
Dexter knows there is a team he wants guarding the bottom of the Sound. He encountered them tracking him or they are just ticking him off doing what they do. He passively surveils and gets the visable front page on the crew. After taking a good look at the team he pegs one of them as a target. They are smart and knowledgeable about the team seemingly but not the dangerous in up close combat, probably the mage. He tracks the mage to his house and does a little deeper digging to verify this threat and getting a handle on his abilities by breaking in when the mage is out. Confidant the mage is a good bet he does a quick misdirection trap. In the apartment, entry way, or parkinglot of the Mages house, Dexter puts something that will draw the Mage to investagate but seem less threatening but interesting enough to focus his attention long enough Dex comes in from behind the mage and dose him with a powerful sedative. Ambush ideas: Parking lot, Ticket on the guys windsheld is heavily taped/glued to the windshield and he becomes engaged taking it off til Dexter comes up behind or he puts 10 or 1w live chickens in his car and when he is going WTF Dex gets behind him. You get the jist.
Dexter immobilizes his victum, probably the Mage or Face, using copious plastic sheeting to secure them to a table in a prepared lair, sometimes in the victums home or very near where he took the victum,(neighbors apt? Boiler room?). He injects him with nanites will he is out. He gets up and Dex interrogates/ tortures the mage/Face to get info on the team, a fun RP extravaganza. Then he has the mage/face call one of his friends to come pick him up as long as he has told him everything and the friend bring 25k. While the victum is on the phone Dexter wounds him and let's the mage/face flip out on the phone to his pal. Dexter leaves them to talk 30 seconds and kills the fee and resedates his victum. He leaves a fuel bomb under the victum with wires to him but it doesn't function. His second target is the guy guarding the ride, the ride/Rigger, or if he keeps rolling after the drop he will attempt to trap the team inside saving their friend.
As they roll in they will be heavily armed and moving when they get to their bud. If they are more subtle this may mess Dex up and he will draw them out with texting a single frame image of their comrade unconcious to motivate them, he will keep the cell off at all other times. He will come from the opposite direction of the victum and engage the first target on his list. He is packing several EMP grenades to immobilize and a fuel bomb to toss under the vehicl and light it up. If the ride stays in motion Dex is gonna use the fuel bomb on the main exit in a FedEx style delivery box with a return notice typed out on it placed by the mailboxes. If they hit those stairs he will fire them up, cell detonator.
Anyway I am rambling but these hit and run tactics and a systematic disabling of the team is the way socio hitter would chip them down and take them apart a bit at a time. They would be put to the question of do we run at some point. You get into their heads the boogie man is gonna get them and he is not a stand up shoot out with a chiipped up football hooligan. They can have fun playing cat and mouse on the investagative side. They can worry about their contacts and dependents. Dexter has no intention of as much as be in the same building with the guys concious he is there so it makes fighting a lot easier on him. Eventually the party may turn the tables and take out old Dex. That will be the a great whale tale for the party, how they caught their Moby Dick. It will be a little more intricate than remembering the initiative rolls.
Sorry I overwrite and ramble. Ideas run wild out of me sometimes.
