So what would you call a drone that looked like this? (I really should stop trying to project everything into SR but can’t help myself!!!):

Decepticon Cat

I know there are various war forms that it could be built from but I wanted to try and create a mechanical drone that a shadowrunner might conceivably own or come up against…

I’ve statted it up as a modified steel lynx (as the artwork for that one seemed like the closest combat drone to this beasty)…comments / suggestions for improvement welcome. I’ve added a ‘wish list’ upgrade package afterwards for further possible mods. I know it’s not strictly RAW but I’ve allowed cyber accessories for the legs as well as the ‘arm’. Overmods may or may not be a go depending on GM discretion. Given that they make this drone prohibitavely expensive I would probably allow them! I’ve tried to keep everything below availability 12…

Lynx [H 0, Ac 8/20, Sp 60, Pi 3, B 4, Ar 9, S 3]
Weapon mount (external, remote-controlled turret), defence [3] & targeting [3] autosofts [5,000¥]
+Walker Mode [2,000¥] +Hydraulic Jacks [6] [+1 / lvl to jump tests, reduce falling by 2m / lvl, 4,000¥]
+Cyber Tail [Full Arm, 4,000¥] +Strength Upgrade [4] [1,000¥] +Cyber Spur [1,800¥] +targeting 3 [melee] autosoft [1,500¥]
Total Cost: 19,300¥

Upgrade Package
Sensors [6] [Camera 6+Smartlink+Lowlight+Thermo+Magnification+Vision Enhance 3 (front), Camera 6+Lowlight (rear), 2 Laser Range Finders (front and back), Motion Sensor (front), UWB Radar 4, Radio Signal Scanner 6] [4,550¥]
Pilot Upgrade [4] [10,000¥] +autosofts [4] [Clearsight, Covert Ops, Defence, Targeting x2, 20,000¥] +Response chip [5] [4,000¥]
Total Upgrade: 38,550¥

Overmod Package [Double Cost?!?]
Turbocharger [Ac +5/+10] [2x1,200¥]
Fuzzy Logic [2x2,500¥]
Chameleon Coating [2x4,000¥]
Body Stabiliser [1] [2x3,000¥]
Optimised Cyberlimbs [Verticalist +2D Climbing, 20,000¥]

So, is there a more cost effective, or just effective way of creating this monster?

Reminds me of the Medusa Drones from the Renraku Arc Shutdown

Hough !
Medicineman

Less of a beast ruleswise, but it could still work:

GM-Nissan Doberman (already has Walker mode) 3k
+ Mechanical Full arm (Tail), Strength upgrade 3 with modular hand (the one shown: consider a harpoon) 7k
+ Pimped Ride (chassis) 2 1500k+

For that Hydraulic Jack idea (should your GM let it fly), the cost should be at least 12k as per the cyberware, likely more (4 legs, "Motorcyle" Gyro Stabilisation unit required). Maybe 5k¥ per level (1-3), 2 slots (walker mod), -1m/level, jump maximums for Agility=rating?

Aztecnology Camaxtli?

Camaxtli is an alternate name for Mixcoatl, and is the god of hunting.

Puuurfect my players are currently assaulting an Azzie stronghold

Great one! I love it, and I'm 'stealing' it

All these criminals here, you could think shadowrun is about robbing, killing, blackmail and kidnapping....tsssst.