Map boss simulations please

Add a purchasable waystone from Doryani and a special map node where we can choose boss and difficulty.
Lock boss and difficulty choices to after we've encountered them in a regular map.

Some of us don't run meta builds and bosses, specially t16+difficulty(4), can take longer. This leaves room for error and with some bosses having 1shot abilities it gets frustrating. It would be greatly appreciated if I could practice the boss fight in a current difficulty environment.