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
The value of X is determined only once, as Rip's ability resolves
Borderless card in every packevery Set Booster contains 14 Borderless cards, with at least 1 Borderless Common or Uncommon card
Because of this, the way Secret Lair drops gain excess value is by having a high number of cards in an absolute sense, with some of these cards likely having inexpensive original printings but that end up having more valuable Secret Lair printings
For those who weren't around back in the day, we had to get the Bitterblossom artist back for this
The first ones to have that happen were the Stranger Things Secret Lair cards, which had Magic native versions in New Capenna