Tirion Fordring, at the Crusader's Pinnacle, wants you to obtain and wear a Cultist Acolyte's Hood and meet him at the entrance of the Cathedral of Darkness, northwest of Icecrown Citadel.
1x Tirion's Gambit
Just this morning, my scouts informed me of a Cult of the Damned procession leaving from Icecrown Citadel to the Cathedral of Darkness, bearing an artifact.
And now I learn that it might be Arthas's own heart... a thing containing the last bit of his remaining humanity.
This is a sign of the Light. As long as such an artifact exists, there is a chance that Arthas Menethil can become a man again!
Meet me at the cathedral's entrance. Be sure to bring a cultist's hood -- we're going incognito.