Hexplosive Minefield at level 4? I would always prefer having your three abilities as early as possible on most champions (except something like AD Carry Ezreal).

I have ran it but I prefer straight magic penetration as it scales better. You can run hybrid pen w/ 4 magic pen blues to make it the same if you'd prefer but I only do that on Orianna but it would work decently well on Ziggs.

Hmm....why not consider greater mark of hybrid penetration as main? Since Ziggs's it synergies very well with Short Fuse.