The Flux Igniter is a Redstone Flux-powered tool added by Thermal Expansion. It is essentially an advanced, RF-powered Flint and Steel. The tool can store up to 80,000 RF and consumes 400 RF per use.
Using the Flux Igniter while aiming at a block will set that block on fire. Using it on TNT blocks will prime them, and using it on Creepers will make them explode. These things can be done from up to 32 blocks away.
The tool can be used up to 200 times without needing a recharge.