Malazan Empire: The Chained One - Malazan Empire

perhaps you've had this thread in the old forum, but this riddles me much:
If Brood's maul/hammer can destroy anything, why won't he use it on the chained one directly? why do all the ascendants and mortals fear that he would be freed if Brood would crush the chains? why couldn't they simply kill him instead of chaining him? is he truly immortal? in Erikson's world even gods can die...
eh, it pains me to have no answers to these questions probably just because the rest of MoI will come out in Poland in August...