In one mp game i had a nice "combination" running with casting black death and one turn later Raven Feast. You get enough (or nearly enough) gems for recasting every turn when using it on high pop provinces so you just need the air gems. However it was more a fun option but my opponent really hate it!
IMHO it has a very niche application.. and most of the time isn't worth it.. then again.. most of the spells in this game are like that really
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Want a blend of fantasy and sci-fi? Try the total conversion Dominions 3000 mod with a new and fully modded solar system map.
Dragons wanted? Try the Dragons, Magic Incarnate nation.
New and different undead nation? Try Souls of Shiar. Including new powerfull holy magic.
In for a whole new sort of game? Then try my scenario map Gang Wars.