Symmetry Sage — ruling 1

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.

Symmetry Sage — ruling 2

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.

Symmetry Sage — ruling 3

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.

Symmetry Sage — ruling 4

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.

Symmetry Sage — ruling 5

If an effect creates a copy of an instant or sorcery spell, this will also cause the magecraft ability to trigger.

Symmetry Sage — ruling 6

If an effect creates multiple copies of an instant or sorcery spell, magecraft abilities trigger once for each copy created by the effect.

Symmetry Sage — ruling 7

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.

Symmetry Sage : règles, fonctionnement et interactions (MTG)

Symmetry Sage is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Flying Magecraft — Whenever you cast or copy an instant or sorcery spell, target creature you control has base power 2 until end of turn.

How it works : Symmetry Sage

Original English text — Wizards of the Coast / Scryfall

#1April 16, 2021· Wizards of the Coast
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.
No other card is named in this ruling.
#2April 16, 2021· Wizards of the Coast
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.
No other card is named in this ruling.
#3April 16, 2021· Wizards of the Coast
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.
No other card is named in this ruling.
#4April 16, 2021· Wizards of the Coast
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.
No other card is named in this ruling.
#5April 16, 2021· Wizards of the Coast
If an effect creates a copy of an instant or sorcery spell, this will also cause the magecraft ability to trigger.
No other card is named in this ruling.
#6April 16, 2021· Wizards of the Coast
If an effect creates multiple copies of an instant or sorcery spell, magecraft abilities trigger once for each copy created by the effect.
No other card is named in this ruling.
#7April 16, 2021· Wizards of the Coast
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.
No other card is named in this ruling.