Quills of Power are a large catagory of magic items that can do just about anything. All one needs to do is write one's desire, it happens and the quill is reduced to dust. Of course different quills have different limitations. Usually they are color coded to make their use easier. They may be metallic (copper, silver, gold, platinum), the rainbow, coded like the cards and bands in some editions of Gamma World (solids versus bands or stripes), or they could appear to be from various monsters and races (the more powerful the critter, the greater the capacity of the quill).

All quills have some limitations. Even the greatest can't rewrite the laws of reality, make large changes to history or give the writer unlimited power. Most have very specific abilities. A Barn Owl's Quill can only alter the population of rodents in an area less than one square mile. Handy for hedge mages and a few others. Adventurers may prefer the Great Owl's Quill. It can alter the senses of a few people, giving them low light vision (or infravision for earlier editions) and heightened hearing. Or even better is the Hawk Owl Quill, which enhances senses and combat ability.

Only a few Quills of Power cause permanent changes, especially to the living. Those that do have a price. It may be behavioral (an addiction to rodent flesh) or physical (facial feathers). In either case it takes Remove Curse or another Quill of the same power to remove the side effect, along with the benefits the original Quill provided.

There is also a danger in using any Quill. If one asks for something beyond its power, the Quill is reduced to ash and the writer suffers something much worse than a side effect curse. Usually this curse is equivilent to an 8th level or higher spell (more Polymorph Any Object than Meteor Swarm).

The source, abundance, limitations and side effects are of course up to you.