Scroll of Animate Dead

Raises 6 nearby dead to fight for 40 seconds.

Source
Thrall can find one in The Oracle, chapter 7 of the Warcraft III orc campaign, The Invasion of Kalimdor.

Tyrande and Maiev can find one in Shards of the Alliance, chapter 6 of the Frozen Throne sentinels campaign, Terror of the Tides.

Kael and Lady Vashj can find one, and buy these from a Goblin Merchant in The Crossing, the secret level of the alliance campaign, Curse of the Blood Elves.