The Arboreal Gulper Frog Mount is dropped by a rare monster in Ardenweald.
The Arboreal Gulper is a frog mount that drops Humon'gozz, a rare monster in Ardenweald's Deamsong Fenn in Shadowlands. However, it doesn't appear with a timer - you'll have to collect an unusually large mushroom to grow this massive mushroom. This can drop any enemy in Ardenweald, so if you have world quests or chests to farm in the area, it's worth killing two frogs with one stone.
Once you've looted the unusually large mushroom, you'll have 20 minutes to plant it at the Humon'gozz spawn location, an interactive part of the environment called the Damp Loam (at the location pinned in the capture of 'screen below). There are crowds here, so you'll want to kill everything nearby, unless you're into fighting a rare monster with over 20 enemies nipping at your heels.
Once the unusually large mushroom has been planted, Humon'gozz will begin to grow, which will only take a few minutes. Once he shows up, anyone can join the battle for the Arboreal Gulper drop (assuming they haven't killed him that day already), so share the info in the general chat. Either way, you'll want reinforcements, as Humon'gozz has a considerable health pool.
The Arboreal Gulper Frog Mount has a 90% drop chance, which is one of the most generous mount drop rates in Shadowlands. This is an account-wide unlock once you've looted it and added to your collection. The Arboreal Gulper has a minor limitation: the frog mount cannot fly, so you will be stuck jumping on the ground. Considering that flying isn't available in the Shadowlands isn't a big deal, but whenever you leave the afterlife after Azeroth's troubled life, you'll want to choose a different mount.
