Thunderfury. A lot of guilds were still putting together Thunderfury runs into late BC.
There was a flask from vanilla that was good for holy pallies in wotlk.
Only cleared MC and BWL in vanilla, from those instances one of our tanks was using Thunderfury for long time in TBC because of its proc.
The reason Stormwind park was completely destroyed was because the night elves there had the audacity to tell Khadgar that Boomkins are superior to Mages in every way. Deathwing just happened to be flying by.
Mark of the Champion, the quest reward from the Phylactery of Kel'Thuzad, was a best in slot trinket for DPS casters vs undead and demons which Hyjal/Black Temple and Sunwell had TONS of.
85 static spellpower.
Darkmoon card: Blue Dragon. Used it for whole TBC as resto druid, insane upkeep partially due to class specific healing.