What does Elixir of Agony reward?

Elixir of Agony gives a choice of High Apothecary Cloak, Meditative Sash, Glistening Stompers, 3,050 experience.

Where does Elixir of Agony start?

Master Apothecary Faranell in Undercity offers it.

The quest log lists it at level 30.

No. The quest exists in Classic Era as well.

World of Warcraft: Forever · quest · level 30

A level 30 quest in World of Warcraft: Forever, offered by Master Apothecary Faranell in Undercity. Recorded by 1 player running the addon.

Item	Given	Item level	Vendor sell
High Apothecary Cloak	as a choice	30	13s 20c
Meditative Sash	as a choice	30	10s 92c
Glistening Stompers	as a choice	30

What does Elixir of Agony reward?: Elixir of Agony gives a choice of High Apothecary Cloak, Meditative Sash, Glistening Stompers, 3,050 experience.
Where does Elixir of Agony start?: Master Apothecary Faranell in Undercity offers it.
What level is Elixir of Agony?: The quest log lists it at level 30.
Is Elixir of Agony new in WoW Forever?: No. The quest exists in Classic Era as well.

What sells at this level, and what to keep from these rewards, is in the level 20 to 30 gold guide.

Source: what players running the addon saw in the quest windows; the quest text itself stays in the game. Every quest seen · Undercity