Recipe drop in Xib and how to go in hardmode

To make Xib going in hardmode you need to kill the twinboss (Dog and his master) before 8 min has passed, when you killed them in that time he will drop an skull that you need to put on the altar at the bottom to spawn the mini ' Yakhmar'.
You have a timelimit to get to the bottom, when you picked the skull up the timer will start (what the time are will come soon).

If the skullwearer dies the hardmode is over, all has to stay alive.

Architec recipe is dropping from the 'Fireboss' after the bridge boss.

Tainted Alkahest drops from the Acheronian Defender (i think, more info will come).