PoE Firestorm, dorfcally builds

Me: Copying from: Damage is about 1/3rd. It insta-kills yellows in t16 maps, but my god it is unbearably sluggish. Especially when mini-packs constantly spawn, needing me to drop one of my 3 firestorms to finish them off. If I had explosions it would be so much better, but I can't squeeze in Impulsa. Self-chill spark would cost too much atm Maybe a 2nd skill for clearing? Or should I swap 6l to rolling magma? It's not ignite focused. Also thought about Fulcrum instead, not sure what damage would be like, I can get the resists eas