I found the El Dorado of Warhammer deals this Black Friday and Cyber Monday

Slaves to Darkness Army Set | £120 £95.99 at Magic Madhouse
Save £24 - The latest Chaos boxset for the Age of Sigmar game has barely left the presses, and it's already seeing a price cut in the sales. With money tighter than ever nowadays, being able to get a discount like that on such a new product is very, very welcome.

Warhammer 40,000 Cadia Stands: Astra Militarum Army Set| £120.00 £95.99 at Magic Madhouse
Save £24.01 - Another brand-new addition to the franchise has seen a healthy reduction at Magic Madhouse, and this time, it's the turn of the former Imperial Guard. This pack is weighed down with everything you need to start an Astra Militarum army, including the obligatory artillery, a walker, and lots of expendable er, helpful Guardsmen to help you push any and all heretics off-world.

Battle of Osgiliath | £125 £98.45 at Magic Madhouse
Save £26.55 - This new boxed-set for the Middle-earth Strategy Battle Game is both highly anticipated and sought after, to the point that Games Workshop only offered a two-week pre-order window for it. With that in mind, seeing it drop onto Magic Madhouse with a £26 reduction is pretty attention-grabbing. It certainly helps that the set is awesome, too; as I mentioned in my The Lord of the Rings Battle of Osgiliath review, it's a great route back into the game.
 

Warcry: Sundered Fate | £110 £87.47 at Wayland Games
Save £22.53 - Although it isn't available at Magic Madhouse, you can pre-order the new Warcry boxed set from Wayland Games at a very good price instead. That's the lowest we've seen, so don't let it slip through the net if you wanted to grab the latest release while still saving the pennies.

Warhammer Underworlds: Gnarlwood | £65 £51.69 at Wayland Games
Save £13 - The latest core box for Underworlds has taken a hefty cut over the Black Friday/Cyber Monday period, and it sat at this price for a while on Magic Madhouse's site before selling out. Luckily, Wayland Games has stepped in with the same offer, so we'd make the most of it while you can. Like I mentioned in my Warhammer Underworlds: Gnarlwood review, this is the company firing on all cylinders.

Warhammer Quest: Cursed City | £125 £99.99 at Magic Madhouse
Save £25 - I genuinely can't think of a more sought-after game from Games Workshop in recent years. That makes this saving on Cursed City (a record low price, actually) a total steal. Well worth a look if you hoped to spend some time hobbying and gaming over the Christmas period.

Kill Team: Into the Dark | £130 £103.99 at Magic Madhouse (out of stock)
Save £26.01 - Even though it's now out of stock, this was one of the better offers I've seen during the sale. No other retailer was stocking Into the Dark, so Magic Madhouse cornered the market a little if you wanted to go outside of Games Workshop itself.
 

The Horus Heresy: Age of Darkness | £180 £143.99 at Magic Madhouse (out of stock)
Save £36 - Another tempting offer that was snapped up fast, this Horus Heresy boxed set flew off the digital shelves. It was comfortably a highlight of the sale, so hopefully it comes back before Cyber Monday is over.