An ashen grey willow with pale leaved tendils obscuring it's gnarled trunk. Sitting in the mire of great swamps, rare even in it's natural environment. The Banshee Willow's bark is known to have magical properties. Travelers beware, these trees seem to attract ghosts and other unsavory undead.
This could have made Johnny Appleseed's job that much easier!
From the same school of thought as, "Hey GM, which book did I just randomly pull from the shelf of the wizards' library?" No plot hooks here, just flavor additions.
Shrinkstools are a powerfully enchanted toadstool, typically found in enchanted forests or other secluded magical locations. Watch your step.
Within these Towers reside some of the most feared sorcerers ever to have blighted the lands of men.
When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.