[Taqwus]

The ability to cause a local drought (perhaps equivalent to a shift to death scale, additional supply penalty?) or cause more favorable rains (growth bonus, additional supply bonus) might seem appropriate. Water + Death also suggests some nasty globals involving well poisoning; there's no reason why poison has to remain purely within the scope of Nature.
A global that would increase income/supply in coastal provinces (lots of fish, say) would be thematic, and would serve as a nice opposite to the one that floods coastals.
A battlefield spell that countered the effects of extreme heat might also be thematic, although not especially fair unless fire got the obvious opposite.