Symmetry Sage

• WWizards of the Coast2021-04-16
  Official Ruling
  Any effects that modify a creature’s power without setting it to a specific value (i.e. ones that don’t affect base power) will apply after its base power is set, regardless of the order those effects were created. The same is true for counters that modify its power.
• WWizards of the Coast2021-04-16
  Official Ruling
  Each magecraft ability has a different effect, although they all have the same trigger condition, whenever you cast or copy an instant or sorcery spell.
• WWizards of the Coast2021-04-16
  Official Ruling
  Symmetry Sage’s triggered ability overwrites all previous effects that set the target creature’s power to a specific value. Other effects that set its power to specific values that start to apply after this ability resolves will overwrite this effect.
• WWizards of the Coast2021-04-16
  Official Ruling
  Some effects instruct you to copy an instant or sorcery card in a zone other than the stack. These copies do not cause magecraft abilities to trigger. However, most effects that do this also allow you to cast the copy, and casting the copy will cause magecraft abilities to trigger.
• WWizards of the Coast2021-04-16
  Official Ruling
  If an effect creates multiple copies of an instant or sorcery spell, magecraft abilities trigger once for each copy created by the effect.
• WWizards of the Coast2021-04-16
  Official Ruling
  If an effect creates a copy of an instant or sorcery spell, this will also cause the magecraft ability to trigger.
• WWizards of the Coast2021-04-16
  Official Ruling
  For example, if you control Archmage Emeritus and cast an instant or sorcery spell, Archmage Emeritus’s magecraft ability will trigger and you will draw a card.

Rulings via Scryfall