Eh. Mono-
is not bad. Of course, against mono giants like
, it pales in comparison, but it is not too bad. Better than mono
at least.

looks pale against every element.
Before the last few patches, the answer would clearly be

, but after hope and bioluminescence I'm not sure.

does have flying weapons, which I love so I can't vote against it.
I think i'm going to go with
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. Its mono is getting weaker duo to more quintessenced creatures, and less emphasis on creature control with the last patches. Afltatoxin only shines in a duo, Death Nymph is not much better than an aflatoxin, and Mummy is only useful in a duo/tri deck, where death is the least used element. (And I know poison decks are awesome, but IMO the best poison decks are water/death)
Air and Death are the elements that need a new mono boosting card, like Hope.