The main rules are from the 5 th and 6th editions, with some new tweaked rules:

• Pursuit rules of the 6 th Edition;
• Charge rules: charging gives you a +3 Initiative bonus;
• Close Combat rules of the 6th Edition;
• New Hit to Chart;
• Shot rules of the 6th Edition;
• Moviment rules of the 6th Edition;
• Musician, General and Battle Standard of 5th Edition;
• Psycology 5th and 6th mixed;
• Aereal Combat. “Striking Glacing Blows”: “The attacker makes all his attacks in the normal way” became → The attacker makes just one attack for model (E.g. Hero on Dragon: you can make an attack with each of these. – An unit of 5 harpies: each harpy can make one attack = 5 attacks);
• One kind of war machine every 1000 points (e.g. max 2 Organ Guns in a 2.000 points Dwarf army);
• Best armour save allowed 1+ (even the magic items can’t improve it)
• Overkill: max number of character’s wounds +3
• Only one Special Save per wound.

You can download the rules from here: Warhammer 5th/6th Mixed Rules