The Everflowing Well // The Myriad Pools

• WWizards of the Coast2023-11-10
  Official Ruling
  The target permanent copies what is printed on the original card, plus any choices that were made when casting the spell.
• WWizards of the Coast2023-11-10
  Official Ruling
  Some descend triggered abilities include intervening "if" clauses (i.e. "if you have [four or eight] permanent cards in your graveyard" in the middle of the ability). Each of these abilities checks your graveyard at the moment it would trigger to see if it does. If you don't have the required number of permanent cards in your graveyard at that time, the ability doesn't trigger at all. If it does trigger, it will check again as it tries to resolve. If you don't have the required number of permanent cards in your graveyard at that time, the ability won't resolve and none of its effects will happen.
• WWizards of the Coast2023-11-10
  Official Ruling
  Cards with the ability word "descend N" have abilities that care if you have at least N permanent cards in your graveyard.
• WWizards of the Coast2023-11-10
  Official Ruling
  Non-copy effects that have already applied to the target permanent will continue to apply to it. For example, if it's a creature, +1/+1 counters on it will still affect it.
• WWizards of the Coast2023-11-10
  Official Ruling
  The triggered ability of The Myriad Pools will resolve before the spell that caused it to trigger.
• WWizards of the Coast2023-11-10
  Official Ruling
  Because the target permanent isn't entering the battlefield when it becomes a copy of a permanent spell, any "When [this permanent] enters the battlefield" or "[This permanent] enters the battlefield with" abilities of the copied spell won't apply for the target permanent.
• WWizards of the Coast2023-11-10
  Official Ruling
  If the copied spell has in its mana cost, X is still 0 for the purposes of determining the mana value of the permanent on the battlefield.

Rulings via Scryfall