The Talisman of Evasion causes attacks against the wearer to miss 15% of the time. Does not stack with Evasion or Drunken Brawler.
Arthas can find one in The Culling, chapter 6 of the Warcraft III human campaign, The Scourge of Lordaeron.
Cairne Bloodhoof 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.
Arthas and Anub'arak can find one in A Symphony of Frost and Flame , chapter 8 of the Frozen Throne, sourge campaign, Legacy of the Damned.
Rexxar and other Heroes' can buy one for 1200 gold from the Orgrimmar Armory, in the Frozen Throne Bonus campaign, The Founding of Durotar.
In the Frozen Throne the tooltip was changed to add: or Drunken Brawler.