Doing Demi's Lacerate Slayer. I want to use War Banner in the Last 4 link slot.

Hi im new to the forum and pretty new to PoE i have an arc witch and a double strike juggernaut so far. I noticed i had more fun with my double strike melee build but i found this lacerate build and it looks fun. I want to work in war banner because ive heard its a really great skill and seems like it would benefit this build pretty well. I dont know what support gems i should link with it. Any help would be awesome