http://www.warseer.com/forums/showthread.php?t=298644 for me it seems that no equipment or special rules work with or againts thunder stoms BRING BACK THE STEGADONS!
Prety sure it's just suposed to be a allways strike last attack at base strenght.... and nothing extra or sneaky in the wording.
Q: Do Stomps or Thunderstomps benefit from any other special rules, equipment or magic items? Or vice versa? (p76) A: No to both questions. Now I'm not an expert of the english language, but here is my interpretation. Stomp and Thunderstomp aren't affected by special rules/magic items on the character/monsters. For instance, if a monster has the multiple wound special rule, it wouldn't transfer to stomp/thunderstomp. That doesn't mean that the enemy being hit by a stomp or thunderstomp won't be able to use his special rules.