This item was part of the legendary crafting materials which were removed from the game in patch 2.0.6 in June 2014.
It doesn't have any use anymore according to the Diablo III Wiki (click here) and I can use the gold, perfecting gems (my old obsession).
The most gold I had at any given time was around 20,000,000 but I squandered it all away most on combining gems.
I just can't help myself. They're so nice and shiny!
The Realm of Trials is an area where players fight waves of monsters to earn higher level Greater Rift Keys.
I tried going at it solo and died at around wave 19. It should be more fun with a group.
This is only found in Adventure Mode in Reaper of Souls or the Ultimate Evil Edition.
Ans speaking of Greater Rift Keys...
Higher level Greater Rift Keystones, enables players to start in higher level Greater Rifts.
Wave after wave of monsters spawn attack you with each wave tougher than the one before.
This process continues until you're unable to finish a wave within the time limit.
Don't forget though: there is also no way to respec your skills or change around equipment while in a Trial.
I might try a different build next time and see what happens.
