Brimhir Glimmerbeard has decided to enslave a party of adventurers, using a magical explosive collar, and put them through an assault course to test their abilities.
He will then have them travel from Naldim to Parabola to retrieve the hammer from the pit fiend Ragareth by whatever means necessary.
Brimhir wants Samirs hammer because the king of Naldims birthday approaches and a gift is due. By presenting him with the greatest gift Brimhir can restore his houses name and fortunes.
Other dwarven houses are after this hammer for the same reasons, though they have been able to hire guilds and adventuring parties more conventionally.