This item is an ultra rare drop from Ultraxion in Dragon Soul on normal and heroic mode. It also has a chance to be listed on the Black Market Auction House.
Here you can buy Experiment 12-B for EU or US Servers.
You'll get guide for getting Experiment 12-B
You'll be able to get Experiment 12-B
Additional budget for Character transfer or Character boost to max level. BMAH Services in Shadowlands now requirement to have a max level character on server, so Trial character will not work.
Free time on evening, if you choose selfplay option