The Horadric Staff
Ahh... The lost Horadric Scroll! What a fortunate turn of events...
As the last living Horadrim, I alone have knowledge of its meaning. Now, to read the Horadric runes it bears. Hmmm...
The Horadric Mages, after binding Baal within Tal Rasha, magically sealed off his Burial Chamber from the mortal realm. Those same Mages also crafted fearsome Horadric Staves and imbued them with the special power to open the Chamber's hidden door.
After nearly losing one to the thievery of a rogue sorcerer, they divided all the Horadric Staves into two parts - wooden shaft and metal headpiece - hiding them separately to safeguard them.
The Horadrim foresaw our current plight and designed the hiding places to reveal themselves to worthy heroes like you.
Collect both parts of a Horadric Staff and unite them using a Horadric Cube. Then, you may enter Tal Rasha's Burial Chamber.
To do it - use the Cube as you would a scroll. When the Cube opens, place both pieces of the Staff into it and use the Cube's transmute power.
You'll be pleased to know that the Cube has other alchemical uses as well...
Six gems plus one sword transmute into a socketed long sword.
You may also transmute two quivers of crossbow bolts into one quiver of arrows, while two quivers of arrows yield one quiver of bolts.
I must leave it to you to discover other formulae.
Staff of Kings
I trust you know how to use a Horadric Cube to unite the shaft with its headpiece.
Amulet of the Viper
Amulet of the Viper is reward for completing Tainted Sun quest.
Yes... You have an uncanny knack for finding rare and valuable artifacts. Of course, you'll have to use a Horadric Cube to combine the headpiece with the shaft.
Carry it with you into Tal Rasha's Tomb. Find within the Tomb the chamber whose floor is inset with the Circle of Seven Symbols.
Place the Staff into the receptacle you find there. That will open the secret passage into Tal Rasha's Burial Chamber.
But, be prepared for a fight - you'll likely have to kill Tal Rasha to destroy Baal.