[quote=Scio]
I'll just repost mine since I'll be editing some other some in. As for weaknesses, not really sure other than the prerequisite of a Haiku. Maybe the fact that I'm only limited to abilities found in literature? Could that work?
[/quote]

How about a time limit dependent on the magnitude/complexity of the object? And possibly a limit on the number of items summoned at once? Those are classic weaknesses which could be overcome simply by practice/training.