Well, there have been tons of posts asking the same question already, so you should be able to find it if you would use the excellent search option of the Forum.
However I'll help you out this once, if you promise your next question won't be "How do I kill Firkraag"
SPOILERS
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-The Hammer of Thunderbolts: in the Mind Flayer Dungeon in the Sewers of the Temple District (you need the key from Tazok in the Windspear Hills to be able to enter)
-The Gauntlets of Ogre Power: in the Planar Sphere in the Slums District (you need Valygar or his body to enter)
-The Girdle of Frost Giant Strength: in the Kuo-Tan Dungeon in the Underdark (you need to summon an animal on the stone statue)
-The Scroll with the True Name of the Crom Faeyr: In the Shadow Dragon's Lair in the Temple Ruins (you need the Umar Hills quest to be able to go there)
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Melusine, High Queen of Fluffies, Archbabe of the Order of the Holy Flame and the Laughing Hyenas, &
Official Entertainer Elf of the BG2 Bar
Your voice is ambrosia