Ruins of Guk - Take the balloon from Firmroot Moot to the Entrance of Guk (level 80+)

The Ruins of Guk: Halls of the Fallen aka Upper Guk (moderate)
The Ruins of Guk: The Lower Corridors aka Lower Guk (moderate to hard)
The Ruins of Guk: Ykesha's Outer Stronghold aka Guk Stronghold (hard)
The Void (level 80+)

Obelisk of Ahkzul (easy) - Upper Moors of Ykesha, path leading south from U.J.L.
Anchor of Bazzul (moderate) - Upper Moors of Ykesha in the Innothule Swamp
Palace of Ferzhul (hard) - Lower Moors of Ykesha on top of the Brokenskull Rock

Located in The Commonlands near the Hidden Canyon griffon tower
Scales from level 50 to 80

Befallen: Cavern of the Afflicted (easy)
Befallen: Halls of the Forsaken (moderate)
Befallen: Necrotic Asylum (moderate to hard)

Located in Everfrost within the tunnel introduced in LU47
Scales from level 50 to 80

Miragul's Phylactery: Scion of Ice (easy)
Miragul's Phylactery: The Anathema (easy to slightly moderate)
Miragul's Phylactery: The Crucible (moderate)

Located in Lavastorm head left after the first tunnel

Scales from level 50 to 80

The Deep Forge (easy)
Najena's Hollow Tower (easy to moderate)

Located in Loping Plains inside a crypt in the Somborn Cemetary

Scales from level 70 to 80

Evernight Abbey (easy)
Mistmyr Manor (easy to moderate)
Ravenscale Repository (moderate to hard)

Located in Fens of Nathsar
Level 80+

Veksar: The Sunken Theater (easy to moderate) - In the Lake of Ill Omen
Nu'roga (easy to moderate) - Just inside the Mines of Nurga
Emperor Atrebe's Laboratory: The Fabled City of Kor-sha (moderate to hard) - Sokokar from Omen's Call

“ To give you an idea of how I rate them, I did Runnyeye 2 and I would rate that Easy to Moderate difficulty. ”
— Kander (SOE Dev)
“ Keep in mind when we say easy that doesn't mean that the entire zone will be easy. That means it should be the easiest to figure out the strategies. They should still be challenging and over time you will figure them out and you will see they are actually fun to run through. ”
— Gninja (SOE Dev)