You can steal buffs from your target as a 70 mage with the spell "Spellsteal". Here are a list of buffs you can steal sorted by classes.
From all classes:
Most trinket effects
Clearcasting
From a Druid:
Mark of the Wild
Rejuvination
Thorns
Regrowth (HoT only)
Innervate
Lifebloom
Natute's Grasp
Nature's Swiftness
From a Hunter:
None that I know of.
From another Mage:
Arcane Intelligence
Dampen Magic
Amplify Magic
Molten Armor
Frost Armor
Ice Armor
Mage Armor
Slow Fall
Mana Shield
Ice Barrier
Presence of Mind
Arcane Power
Fire Ward
Cold Ward
From a Paladin:
Righteous Fury
Divine Protection
Blessing of Protection
All Paladin Blessings
From a Rogue:
None that I know of.
From a Priest:
Fortitude
Power Word Shield
Shadow Resistance
Spirit
Renew
Symbol of Hope
Inner Fire
Elune's Grace
Shadowguard
Prayer of Mending
From a Shaman:
All Shaman shields
Natute's Swiftness
From a Warlock:
Voidwalker Sacrifice
Demonic Sacrifice
Demon Skin
Fel Armor
From a Warrior:
Battle Shout
Commanding Shout
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