Is there a guide for finding specific specters in which maps/areas?

It has been a really long time since I made a summoner but was just curious if there was a guide out there to tell players where to find certain specters for 3.0? For instance, previously I did Flame Sentinels I think I would get them from Solaris but probably too low level now? So where do you get them? It used to be that not many level as summoner but did arc or some other spell is that still generally true? I remember keeping anything alive used to be difficult before level 50 or so. Any hints appreciated.

what are you talking about

maybe try https://pathofexile.gamepedia.com/List_of_unique_boots