With the recent patch tweak to Korvaak’s and Primal…
I thought I’d note a potential pyro pet idea that is all fire: Swarmling Pyro (+Hellhound). crazy swarmling + Hellhound pyro
the swarmlings have 100% fire damage conversion and in theory this should extend to their retaliation:
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strong fire attack 350-ish fire at 1000%ish damage.
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strong retaliation (2000 at 1000%).
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throw mines or some other skill to proc the swarmlings.
you could hybrid it but it only has ~1200% character fire and needs some sustain tweak. I’ve not tested it. Maybe something for later when you get bored 
(It’s not something to start with…)
Seriously, though…Stupid dragon has listed most of the smoother progressions.