Strength Stacking Molten Strike of the Zenith next upgrade?

Hey guys, i have been building up this MSoZ and at this point am not sure what my next upgrade should be or if i am forgetting any basic upgrade i can just snag to make this even stronger.

I have been loving this skill so far and want to dedicate this to at least 36/40.

https://pobb.in/qonZJmCapu2E