What grabbed me the most, though, were the mercenary rules. You get an allowance of points to hire mercenaries to the tune of 100 points for every 500 points in your main army so a 2,000 points army gets 400 points to spend on mercenaries. You can pick from any Army Book you like with no restrictions other than needing a character to be your Mercenary Captain.
What I like the most is that your mercenaries can change sides. If they flee and pass a rally test you roll a dice, on a 5 or 6 they stay loyal to you but on a 1 to 4 they waver. You and the other players dice off and the winner takes control of the mercenaries.
I just keep coming up with ideas for mercenary warbands to add to my armies or my friends':
My Vampire Counts could march to war besides some Empire Free Company to represent Sylvanian Peasant Militia.
An all Ethereal set of Vampire Counts models to go with an Empire army, representing the “retinue” of my friend Matt's Lore of Death Battle Wizard: a Cairn Wraith, a Tomb Banshee and a unit of Hex Wraiths. If they change sides it represents him losing control and them turning on him.
There's a piece of art in the Tomb Kings book that just offers a fascinating visual: Tomb Kings and High Elves standing side by side. I rather like the idea of some Swordmasters of Hoeth with a Loremaster for their captain marching alongside the undead phalanx.
Bretonnians are a tricky one, it's always been in their background that they don't hire mercenaries for honour reasons but I don't see why a warband of their close neighbours the Wood Elves might not tag along for a battle or two.
As for the Dark Elves I'm working on at the moment, some Chaos Knights with the Mark of Slaanesh or some Hellstriders would fit my Cult Of Pleasure theme rather nicely.
If nothing else this supplement is providing me with a wealth of inspiration. In a week or two Matt, Dave and I will be trying out the rules and we'll see how it works out in practice.