If you give the skink chief a bane head and go character hunting then he's definately going to die. Unless you only plan to charge lone wizards with them. Most characters will bum shaft a skink priest. I still use a unit of 3, but sadly its just because I only recently got the models, and feel I should at least get some use out of them :S
The last time that I used a skink chief on terradon was against VC. I equipped him with a javelin, the Fencing blades, and a shield. Anyway, I charged a unit of ghouls (with a vampire count). I issued a challenge. He accepted. My skink chief got 2 wounds through and the Terradon brought the 3rd home with the stomp attack. VC started crumbling after that. It was awesome. I usually run a unit of 3 terradons and a skink chief for the war machine, wizard hunting aspect.