lol, patio, I can read spanish, and I understood this spell very well..
I haven't tested it, but looking at the triggers posted, there are just a few things that could be fixed pretty easily for it to work better.
Change "Unit - Dreadlord 0000 <gen>..." to "When a unit casts a spell" so that it works for any unit, which fixes the MUI problem.
Conditions are perfectly fine to be MUI
Remove "pause caster" and "make caster invulnerable"
Reduce the number of flame strikes, somewhere between 30 or 50 is way better than 100. This cuts the lag and looks just as good to me.
(correct me if I'm wrong on this one, guys) You can reduce the number of dummy units by placing one at "position of casting unit" and making that 1 dummy cast the spell at each point in the spiral.
Daelin's tutorial should explain how to make the spiral correctly and reduce the size of the trigger.
Overall, I like this spell and I think it'd be nice with a few fixes. I think it's worth a 2/5 until it's fixed, then it may be a 3 or 4.