I found three of them right next to one and other, and two duel witch Spawers and a load of big villages, I got a portal gun from a temple and even found a division sigil in one of the blacksmith or other chests laying about. But the biggest thing I found, well exploring was in fact 3 whisp spawners back to back not long after I found my portal gun, I have yet to move them but its still pretty great I might in fact post the seed for it at some point if anyone wishes to check out the seed on the whole. It has at least three gaint factiozation guys. And two meteors and loads and loads of village space. If you go to Twilight Forrest and get a bird morph or find a bat its pretty straight forward, the Jungle has two temples and the Jungle is not far from the start more or less. But I am pretty sure you need a Aura node, just as the spawners in the wild have so do they need it. Just as for Mooshrum spawners require the proper dirt.