Multiple Objectives

[Phoenix_Wing]

How would i go about multiple objectives triggering an event? I have 3 plant bomb events, and i want them to trigger a giant explosion after each of them has been placed, but how would i make a trigger that checks to see if all 3 have been completed and then delays the next objective from turning on until the bombs go off? Sorry if thats confusing, but heres what it is:

1. Plant Explosives
Plant Explosives
Plant Explosives
------------------------> The trigger would go here after all 3 are finished.
2. Move onto other objective

Also what sort of emitter would i use to create a giant explosion feel? I can use basic ones but they dont quite fit the explosion feel.