Let's say we want to make a Ranger that makes it his life's goal to hunt undead.
So let's go straight Ranger 20; we forgo the Animal Companion to get his Favored Enemy bonus to Attack rolls.
We're going to say that he's human, so he's grabbed Wise to their Ways, Unquenchable Flame of Life, Nemesis, and the Supernatural Blow feats on the way to 20th level. He buys an Enemy Spirit Pouch aimed at Undead, and a scythe.
Then, he casts Mark of the Hunter on Mr. Powerful Undead Creature, and Foebane on his Scythe.
Then, he closes.
He gets a +21 to hit and +3d6 damage against the Undead creature; whenever he would threaten a critical, he adds +8d6 damage, thanks to Supernatural Blow.
On top of that, he has a +32 to saves vs. the Supernatural abilities of undead... yeah, he ain't gonna fail (he also has a +16 against all of their Extraordinary and Spell-Like abilities, as long as they don't come from Class Features in the case of the Supernatural abilities...)
All I need is a way to get Favored Enemy bonuses to AC, and I'm set...
