A lot of people rank omen of Famine before War for the life drain, but i've found that a lot of the time yorick isn't focussed because he is a little tanky and generally isn't a big damaging force to worry about. This build flips that and makes omen of war do some big burst while you still have the support/harass from pestilence/death and are quite tanky. Sometimes i will make it a little tankier later into the game if i find myself being focussed, but generally its not an issue. Try the build out for yourself before you slate it.