i try to take 2 or 3 if not more.

You can take three at most in a 2000 point game as you need to have either a tomb king or tomb prince

i use 2

2 mostly

gotta have two. if not for all the spells then because you might be able to confuse your enemy as to which one is really the hierophant =) j/k but seriously you dont want to field one unless yorue a numbskull