I am glad this was only for the 50th anniversary event. My friend Jimmy's
Acererak the Archlich deck would be even more annoying with this.
That said, the path I would take would depend a bit on what deck I was using, and What stage of the game I was at. Early in the game Autie's Teahouse into
Mountain Pass seems the right way to go. Then I would prob go Grymforge to give myself options on the next Venture. On the first trip through,
treasure tokens prob beat out card draw (Jimmy's Acer would always go for the
treasure to cast Acer more times). The last three rooms would almost always be Gauntlet of Shar - Circus of the Last Days - Ansur's Sanctum.
Looking at this thing from
Acererak the Archlich's perspective... 8 rooms that provide 3-9 mana and a token copy of Acer that deletes itself to venture an extra time. Assuming no discounts, you need to produce 18 mana to guarantee to get all the way through. Acer decks always seem to find their discounts though, so let's assume you are casting Acer for a Black mana. You need 4 mana to guarantee getting all the way through and the dungeon has the potential to provide more mana than is needed to finish all the rooms. If you add in a
Phyrexian Altar, you can hit the Emerald Grove for a token instead of
Scrying and make 3 skeletons instead of a copy of Acer. with this you have less than a 7% chance of the dungeon providing less than enough mana to get through it again. The Dungeon is also thinning lands out of your deck, increasing the average damage of Ansur's Sanctum. Even in early turns it is giving you land ramp, which is rare in mono-black. Thank Oghma Acer can't use this thing outside of one event.