Originally Posted by
dreamlitz
I wanted to point out that while Slashley's explanation is correct, KitKat's answer about not worth spending eidolon orbs on Cthugha is also generally the correct one for a different reason. That is Adramelech gives 45% elemental at MLB, while Cthugha only gives 40% char atk at MLB. Adramalech's atk stats are also much better than Cthugha. Cthugha also gives 20% HP so you might want that if you can't get your hp high enough to tank an OD or two.
For fire, usually ppl go for dps though, assuming your assault value is at least 117 (9 x SR disaster weapons) Adramelech comes out ahead in every conceivable scenario except the one Slashley pointed out, where you have friend Belial + soup weapon + elemental advantage, where Cthugha might come out ahead but only slightly.