How to murder your players:
1. Get a hoard of Gerbils. (any diminuative critter will do. It must have an int of 1)
2. Outfit each diminuative gerbil with a diminuative suit of leather.
3. Train each gerbil in Armor use trick. Attack Trick. Fly Trick.
4. Get the reach metamagic feat and Extend metamagic feat.
5. Learn the spell
Bristle, a second level wizard spell, Fly, a third level wizard spell, and Invisibility Sphere, a 3rd level wizard spell.
6. Buy two Rods of chaining.
7. Memorize Ranged Bristle 3 times. (3 4th level slots), and memorize ranged Fly three times.
8. Make sure you have at least 1 minute before the PCs arrive.
9. Have your 14th level wizard cast ranged bristle with the chain metamagic rod three times. That's 45 Gerbils with Bristle for the next 13 minutes, give or take.
10. Have your 14th level wizard cast ranged fly with the second chain metamagic rod three times. Now your gerbils can fly at 60 feet a round.
11. Cast Invisibility sphere on the leader gerbil.
12. Keep the flying gerbils in a giant cage with a huge door you can throw open when you need to.
13. When the PCs arrive threaten to open the cage if they don't surrender at once. When the PCs laugh, throw open the cage and cry, ATTACK MY MINIONS!
14. As the players snicker, a cloud of Leather Clad, spike covered gerbils attack the nearest target within 60 feet and appear as the invisibility spell ends. Each gerbil does nothing, but just the act of TRYING to attack triggers the Bristle spell, which results in a free attack at 2d6 damage. Uptyped SPELL damage, I might add. (add fell drain if you are so inclined to turn the PCs into wights in short order.) The spikes have an attack bonus equal to your CASTER LEVEL (which is 14.) Plus, being diminuative critters fighting Medium Sized critters, they get +4 to hit (or if you can fine a Fine sized critter that you can put leather armor on, you can increase this to hit bonus to +8)
15. Witness the PC's horror as they realize that the gerbils, being diminuative size can each bunch up flying into your square, 16 at a time. (Make it 3 groups of 15 to be easy on the DM) Hope you got a whole bunch of AoOs. Once in your square, you will get hit with 15 +18 to hit, 2d6 attacks. Assuming the PCs have an AC of 29, Each Gerbil will still hit 50% of the time. That's 7 successful hits. At 7 points of damage, that's 49 points of untyped damage a round to three PCs.
Of course, one fireball or what have you will dramatically change the outcome, but one round of flying, leather clad, spiked Gerbils turning your PCs into pin cushions should be enough to establish this as a night they will NEVER forget.
16. ???
17. Profit.