AV's Sacrafice the weak is good enough. Alexis also has breeding pit.
If Infernal land will spread to Lanun civ, it will be good, as AI often build farms as Lanun WITHOOUT santation (gives +1food on farms IIRC) or agrigultural civic.
Making hell terrain rivers NOT be a source of fresh water would also make it hell for any other civilization besides the infernal...
They are Infernals and are turning World of the living into hell, dont they ? Thats an argument for I say. Another thing is that this will increase meaning of Armageddon counter.
As for StW civic. Cities can have 2 times more population and grows 2 times faster and can have more production at lower population (1 fish with lighthouse +city gives 8 food, thats 8 titles to work on, 1 fish, 7 plain hills).
Forgot to add, that if Infernal lands will take away farm making possability from rivers, cities will lose population whitch will lead to weaker civ power (united offensive vs Infernals needed, diplomacy will have higher meaning, but AI doesnt like to agree to war with much stronger foe...) and thus The Four Horseman will last longer, and will hurt even more.
Unballancment often is a fun factor. Make Armageddon growth, pay for it. Easy to say if your Elohim, but note that all non-AV gets -3 disposition to those that rise armageddon counter. This may be what we need to make united offensive vs Infernals.