Arcane Nexus

[Evilhomer]

It is generally considered the most powerful global spell in the game(i would probably put forge of the ancients at second) in all but the smallest games. With so much magic flying around late game having it up for even a single turn will probably net you some profit and the only real disadvantage in multiplayer is that it pretty much lights you up as the number one target for most nations.

I would take gift of natures bounty any day over forge of the ancients (atleast if im using a decent dominion value). Arcane nexus is indeed absurdly good, but the other nations tend to alliance themselves against you.