Attack speed marks are a must for skarner. Same with the armor seals. With the glyphs you could go flat base MR if you want to be more tanky at first or you could use a mix of both for both late and early game. As for the quints you could go all movement speed if you want to be able to get closer to people faster to get your slow off. Also if you don't want to be blue buff dependent you can get some mana regen glyphs, but i don't recommend it, it would be better to just buy some mana potions.

If you are doing very well and not dying then I would recommend that you get a Infinity edge or a hextech gunblade instead of a warmog's. If you are dying pretty easily then I would recommend that you get a phage second instead of last for your tri force and possibly get a Guardian Angel instead of the phantom dancer. Also buy a few mana potions if your going to give your blue to your mid.

The reason of not getting fracture early is because when you are chasing people down you have to stand in place for a small bit to cast it.

With this skarner build try to get at least two kills before letting your lanes take them.

Invading is not a bad choice for skarner. As always if your going to invade buy boots first.