Won't work, cause the point of his spell is: nobody should be able to cast spells INSIDE the region.
E.g. When the bloodmage is not in the region, he still can cast flamestrike in that region. The point of the spell is: wether inside the region or not, spells should not have an effect inside that region. Like a magic immunity for a region instead of a unit.
(that's what I think Wolf Prince wants)
My solution would be:
Trigger 1
Event: Unit enters region (Nospells)
Action: Unit - Add Magic Immunity to Entering Unit
Trigger 2
Event: Unit leaves region (Nospells)
Action: Unit - Remove Magic Immunity to Triggering Unit
Trigger 3
Event: A Unit finishes casting a spell
Condition: Ability being cast equal to (thespell)
Action: Region - Move Region (Nospells) to Target point of ability being cast
Trigger 4
The region should be resetted to a location (with pathingblockers) when the spell ends.
If more units have this ability, there should be more regions. I don't know how, but I think you should be able to create a region with size = the spellregion... Or you should pre-make alot of regions, and set a certain region to a certain unit (so that whenever that unit casts that spell, only that 1 region assigned for that specific unit will move)
One thing should be checked out: if you move a region, will units that suddenly appear to be in the region (without entering it) be considered as entering units? Same for leaving units... They probably will, but you never know...