Using fire in a ceremony is a very powerful way to transform energies. If you want to let go of something that is not serving you anymore, giving it to the fire is a very powerful way to release or transform it. Fire is the only element humans have not managed to make toxic. The earth is poisoned, the air is poisoned, the water is poisoned and the ether is poisoned. But we can’t touch fire.
On the flip side, fire can destroy a lot. Which reminds us of staying gentle and humble with it’s power.