Most military aerial flares are made from magnesium powder, plus whatever else they need for other effects like color. If you use really finely powdered magnesium, it will flare up very quickly, which may or may not be what you want. If you shave magnesium off a firestarter block, you will get shavings that will probably go up a little slower. Most magnesium burns will spit out hot sparks that will destroy a UL shelter.
If you want super hot instead of super bright, then switch over to thermite, which is iron rust plus aluminum powder. That can be used to melt through a steel safe.
I would think that a normal firestarter needs to catch a spark and make a moderate amount of fire and heat, and that is all.
If you light up the whole Ziploc bag at once, they will see the light in Las Vegas.