One of the cooler things out of the zombie invasion is the quest rewards. The Argent War Horn stands as one of the most "epic" of all the rewards. This trinket will summon an Argent Knight to your side. He's got some spiffy abilities and stats. Let's take a look:
HP - 2442
Mana – 2434
Damage: About 100 melee and about 150 crusader strike on a level 60 mob.
He also has some spells:
Heal: Heals a person for around 700, often times casting when the person is at 25% or lower health.
Blessing of Protection: Target becomes immune to damage. Unknown when he casts this.
Crusader Strike: A powerful attack that increases holy damage done to the target.
The down side to this guy is that he's only level 60. That's kind of weird given that the trinket requires level 70 to use. I wouldn't be surprised to see his level increased to 70 in some future patch. However at the same time they might leave him at 60 just in order to keep this trinket as more of a joke item, rather then making it anything useful.
You can get this guy by spending 40 Necrotic Runes at the Argent Dawn Quartermaster in Light's Hope Chapel in Eastern Plague Lands. In order to access the Quartermaster you first have to finish the two scourge killing quests, which we've already covered.
Once you have the trinket, equip it, active it someplace and enjoy. You'll notice him appear off in the distance and run towards you into battle (see the video above). He is your personal knight in shining armor after all, and he has to make a stunning entrance. He'll fight at your side, heal you and your allies, and even BoP folks if necessary.
And then just like a true Paladin, the bastard bubble hearths when he's had enough.