So this situation came up at a Reg REL tournament yesterday.

Anson controls an Alhammarret's Archive, while Noah controls a Chasm Skulker. Anson casts Day's Undoing, but the players were unsure as to how the effects would happen. I ruled that Anson would draw 14 cards off Day's Undoing, and Chasm Skulker would not get counters since those triggers would be removed from the stack by the resolution of Day's Undoing. Was this correct?

Similar question: If a player controls Alhammarret's Archive and a Monastery Siege set to Khans, how are those resolved? Will they draw three cards, then discard one? What if they control multiple Sieges?

Your Day's Undoing ruling was correct. The replacement effect from Alhammarret's Archive is applied as normal to the cards being drawn from Day's Undoing, and while Chasm Skulker's ability also triggers during this process, those pending triggers are wiped out by the process of ending the turn.


As for the interaction between Alhammarret's Archive and Monastery Siege, your guess is pretty much correct. The player will draw their normal card for the turn, and then when Monastery Siege's trigger resolves a few moments later they will draw two cards, then discard one.

Additional Sieges will operate the same way as the first, so with multiple Sieges the player will draw once for the turn, then draw two and discard one for the first Siege, then draw two and discard one for the second Siege, and so on and so forth for however many Sieges the player controls.