Brace yourself, Seraphon faq is out.
Major surprise for me is that they chose to make the bastiladon unrendable until he is bracketed
" An unmodified save roll of a 1 always fails. When a save roll is modified by the Rend characteristic of an attack, it can never be modified to less than 1. When a model has a Save characteristic of 1+, modified save rolls of 1 are successfully saved. This means, while the Bastiladon has a Save characteristic of 1+, only unmodified save rolls of 1 will inflict damage regardless of the Rend characteristic of the weapon used for the attack."