[Not another shrubbery]

Originally Posted by Kromm

Maintenance has nothing to do with it. You're maintaining the spell on all those original victims -- like a Regular spell -- and not on the area. As a general rule, Area spells are simply a way to mass-cast Regular spells on lots of people. Very few Area spells create a persistent zone of magic, and those that do usually say so.

Huh... I guess that explains the relatively low energy cost, then. And when maintained, it's only on victims that remain in the original AoE, right?