Throughout the anime and manga, they make it a point that Dark's magic is very powerful, and could hurt humans very easily. In the anime they used that rutile (I believe that's what they called it, my memory isn't so good) to keep Daisuke safe, and in the manga it's very obvious it hurts the poor red-head if Dark uses too much.
So, just how strong do you think it is? How much damage could it do?
Also...do you think that Dark must use a feather to cast his magic, or do you think the feather merely helps in some way?
~Zakura-chan