Obtain Invincible from Arthas in Icecrown Citadel.

Obtain The Horseman's Reins from The Headless Horseman in the Scarlet Monastery during Hallow's End.

Owner of Amani War Bear.

Obtain the Ashes of Al'ar from Kael'thas Sunstrider in Tempest Keep.

Obtain the Swift Razzashi Raptor from Bloodlord Mandokir in Zul'Gurub.

Obtain Mimiron's Head from 25-player Yogg-Saron with no Keepers assisting you.

Obtain the Swift Zulian Tiger from High Priest Thekal in Zul'Gurub.

Defeat Yogg-Saron in Ulduar on 10 or 25-Player Pre-Nerf difficulty, before the release of the next raid tier.