He's probably only using the Gorgon's Chain. It effectively grants him 5+
FNP, 3++ and Eternal Warrior. He's probably also trying to roll for the Flesh is Weak warlord trait which buffs his
FNP to a 4+. Not to mention that Iron Hands characters will regenerate a wound on a 5+ at the end of their turn.
This is, incidentally, the item that enables
Chapter Master Smashfckr. It's basically the single best defensive item in the game, and can keep a bike chapter master alive as he dives directly into the maw of the enemy army. If you give this item to a MoF, and then that MoF hides inside a Land Raider or behind
LOS blocking terrain, he can be next to impossible to kill. I'm skeptical that he survived 100+ like the
OP claims, but this sort of character could easily survive 20+ games in a row if you play him right. If he's playing against smart players, they'll probably just be ignoring the MoF, as shooting him enough to kill him has a high opportunity cost.