Multiple-round Attacks

[Mr. Death]

With Evocation, you can devote a shift of power to keep a block or maneuver going for multiple rounds. What about attacks? Could Harry, say, cast a 6-shift fire spell where it's Weapon:3, affects a whole zone, and keeps blazing for two solid rounds?

I realize for most types of attack evocations, this'll be simply impractical, since they have to be aimed and the wizard in question will almost certainly be doing things between turns that would break off his aim (dodging, for instance), but for some situations it seems like it might be useful to be able to keep the pressure on for an extra round or two--like making a zone inhospitable for a couple turns, or letting a heat drill keep pounding on a stubborn door while the wizard defends himself from the goons on his tail.

Thoughts?

[Tedronai]

The closest thing to what you want that is present in the RAW is the example spell, Orbius, which is itself the focus of notable contention on these boards with respect to its balance implications relative to other casting options.

[Sanctaphrax]

This has been discussed before, over here.