Personally I just play fire in my arcane gear and wear 0 crit and play firestarter, huge 600~ dmg on pyros, FB. 52 scorch, 310 crit fireballs.
W firestarter you hit pets, totems, 90% targets to get pyroblast. You can cast a fireball at a totem with Heating Up, and cast pyroblast mid air, to gain the Pyroblast buff mid cast and shoot 2 out at the end. It’s strong
For kill combo go for 90% ppl to hit with a pyro and fireball at the same time with fire blast up, shoot the new pyro and blast. If the pyro crit (the only rng in the combo) you got a 3rd pryoblast to shoot out. If it’s a leveler he probably died already assuming ur running glass cannon only versa/int stack