What does The Power to Destroy... reward?

The Power to Destroy... gives Ghastly Trousers, Dredgemire Leggings, Gargoyle Leggings outright.

What level is The Power to Destroy...?

Its level has not been recorded yet; it shows once a player accepts it with the addon running.

No. The quest exists in Classic Era as well.

World of Warcraft: Forever · quest

A quest in World of Warcraft: Forever in Undercity. Recorded by 2 players running the addon.

Level, giver, pay and objectives show once a player with the addon accepts the quest.

Item	Given	Item level	Vendor sell
Ghastly Trousers	outright	18	4s 25c
Dredgemire Leggings	outright	18	5s 33c
Gargoyle Leggings	outright	18	6s 43c

What does The Power to Destroy... reward?: The Power to Destroy... gives Ghastly Trousers, Dredgemire Leggings, Gargoyle Leggings outright.
Where does The Power to Destroy... start?: It was picked up in Undercity.
What level is The Power to Destroy...?: Its level has not been recorded yet; it shows once a player accepts it with the addon running.
Is The Power to Destroy... new in WoW Forever?: No. The quest exists in Classic Era as well.

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