I use my powers as a shaman and conduct a powerful cleansing ritual to dispel your ghostly friends. Then I surround the hill with a powerful energy shield that protects me from any and all comers. MY HILL!
Having previously enfused my life essence into a great ring of power, my wraith buddies resurect me in all my sorcerous glory and I sweep you and your pitiful undead rabble of the hill with my enormous Orc army. MY HILL!
With my mana energised from the dissipation of my undead army, I create a gigantic fireball of light that is twice the brightness of the sun, rendering you, the wraiths and your orc army blind and screeching for the nearest sinkhole of darkness you can find. MY HILL!