While proliferating twice, players can't respond between proliferating the first time and proliferating the second time
The way Sagas work is they put a lore counter on themselves when they enter the battlefield, and then anytime a lore counter is put on a saga, the corresponding triggered ability will resolve
I like this card more than Vizier of the Menagerie because it decouples the creature from the card draw engine
Other creatures you control enter the battlefield with an additional +1/+1 counter on them for each mana from a Treasure spent to cast them." The card is good for sure, but it's on this list because we feel as though it represents the way treasure tokens have evolved this year
In other formats, youd simply have to pray a Liliana planeswalker turned up while you had this spell in hand to get full value out of it, but in Oathbreaker, you can guarantee this happens by choosing a Liliana planeswalker as your oathbreaker