Keywardens (Torment 1+)
Key of Bones - Act I, Fields of Misery
Key of Gluttony - Act II, Dahlgur Oasis
Key of War - Act III, Stonefort
Key of Evil (random) - Act IV, Silver Spire Level 1

IM Bones: Leoric's Regret: King Leoric/Maghda in Realm of Discord
IM Gluttony: The Vial of Putridness: Ghom/Rakanoth in Realm of Chaos
IM War: The Idol of Terror: Siege Breaker/Zoltun Kulle in Realm of Turmoil
IM Evil: The Heart of Evil: Uber Diablo in Realm of Fright

Drop rate in Torment:
T1: 25%, T2: 28%, T3: 33%, T4, 38%, T5: 43%, T6: 50%

Kanai's Cube:
The cube is in the Elder Sanctum within the Ruins of Sescheron in Act III on Adventure mode.

Merchants:
Squirt the Peddler: 25k Wirt's Bell, Essence of x gems 500k, Hellfire ring Designs 2m

Note: new legendaries in torment 1+