One of my coolest and best models the C'tan Shard of the Nightbringer. This guy has killed 2 Dreadnights and sent the 3rd one running for an epic win. I won't lie though I have used him wrong before and got owned, but a very useful model because he makes all difficult terrain dangerous and all dangerous terrain test failed on a 2 and 1. Makes him the ideal piece for Cities of Death and Zone Mortalis.
I didn't like the little blade that he came with and it was always falling off anyways so Drak gave me a tyrnaid arm to use.