when you go up to Blastmaster she starts walking then gets ambushed by a buch of non elites. once the charges are set GET OUT OF THE CAVE it kills you.

It's essentialy an escort quest, but you only travel a few steps from where you meet her.
Event was explained very well above so no need to elaborate more on it. Although I would like to add a suggestion regarding looting of bodies. DO IT QUICKLY or get someone in your group (if grouped) to take care of the looting. Once the explosions go off and re-close the side tunnels, you won't be able to access any unlooted bodies inside them obviously. Just trash mobs...but you never know what they might have on them. ;o)

Edit: I might as well post the link to Grubbis' loot table http://classicdb.ch/?npc=7361#drops and Chomper's http://classicdb.ch/?npc=6215

Once you have finished her event, check each barrel on her stage to see if it has a (Item #5740) in it.

Talking to Emi Shortfuse starts an event where waves of Troggs will attack her as she attempts to light explosives to seal up the Trogg caves. When she warns you that a blast is about to occur, make sure you leave the cave she is about to cave-in. Just before she destroys the second cave, Grubbis and Chomper will spawn and attack.