Who knows? 

As its about a year since the achievements were added, it could make sense that there is another now. 

There doesn't seem to be any reference to it on the internet, but it could be so new,no one has had time to publish anything, though sometimes it's thought better to keep things under wraps. 

Now I just found some obscure indication that it does exist.???

I don't know it might be  a first April prank 

Never thought of that, but if its hidden somewhere obscure so few people notice it, theres not much achievement there.  Yours was the first reference to its possible existance, or now ,trick.

Of course pecemaker sounds  like 'whatever could that be'

Where did you see the suggestion, Marina?

trying for Bifrost 4

I have 50 Periodet and used 20 7 week peace treaties, attacked a town and shutdown, 3 hrs later nothing. 

Please advise

Your palace must be level 30 or above and the Peridot must be legendary.

Whether the fifty legendary Peridot must be fused within any particular period relative to wearing the 20 week shield I do not know.

es muy facil saber si hay un logro nuevo. los que llevamos tiempo jugando lo sabemos. Agendas a ciertos jugadores, sobre todo una jugadora miras sus logros y si hay un logro nuevo lo tendra un mes antes que nadie.