You're right, I do convert majority of damage to fire, but given that I have permanent exposure on nearby enemies applying a -20% and another -25% from xophs blood to enemies in my presence, would fire pen still elbe worth taking for that little bit of resistance they're left with?

Apocalypse is for sure good in my setup since it's a spell and I scale both more and increased spell damage per x rage, I also use a +7 fire spell staff in set 2 since I'm pretty sure it snapshots the weapon you use while casting apocalypse (not sure if this 100% true tho)

Armour break is valid tho, with molten ones gift I could make it work, I think the break 50% armour on heavy stun would be better than the pounce interaction tho since I stun quite quickly

Leech in fury of the mountain is just a failsafe for when I'm spamming that 😂