One Japanese player told me.
play 5 Treasuries
buy and gain a Cavalry
topdeck those Treasuries
play them again
play Cavalry as Horse
infinite coins
Is it a correct behavior?
Would work better with Villa, but yes, that does seem to be valid. And while this particular combo wouldn't come up very often, Villa/Cavalry + Treasury with any kind of draw in your hand would allow you to play your Treasuries multiple times
Which makes me wonder why Treasury was changed from "at the end of your turn" to "at the end of your buy phase"
That errata on Treasury, I just realized, means also that it doesn't work nearly as well with Changeling, since you can't trash a Changeling for a Treasury unless you don't topdeck it