Sigil Tracer — ruling 1

Since the activated ability doesn’t have a tap symbol in its cost, you can tap creatures (including Sigil Tracer itself) that haven’t been under your control since your most recent turn began to pay the cost.

Sigil Tracer — ruling 2

If the spell is modal (that is, it says “choose one —” or “choose two —”), the choice of mode(s) can’t be changed.

Sigil Tracer — ruling 3

Sigil Tracer’s ability can copy an instant or sorcery spell that isn’t targeted.

Sigil Tracer — ruling 4

If the controller of the original spell chose to pay an alternative cost (such as prowl) or an additional cost, that choice is also copied.

Sigil Tracer : règles, fonctionnement et interactions (MTG)

Sigil Tracer 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

, Tap two untapped Wizards you control: Copy target instant or sorcery spell. You may choose new targets for the copy.

How it works : Sigil Tracer

Original English text — Wizards of the Coast / Scryfall

#1April 1, 2008· Wizards of the Coast
Since the activated ability doesn’t have a tap symbol in its cost, you can tap creatures (including Sigil Tracer itself) that haven’t been under your control since your most recent turn began to pay the cost.
No other card is named in this ruling.
#2April 1, 2008· Wizards of the Coast
If the spell is modal (that is, it says “choose one —” or “choose two —”), the choice of mode(s) can’t be changed.
No other card is named in this ruling.
#3April 1, 2008· Wizards of the Coast
Sigil Tracer’s ability can copy an instant or sorcery spell that isn’t targeted.
No other card is named in this ruling.
#4April 1, 2008· Wizards of the Coast
If the controller of the original spell chose to pay an alternative cost (such as prowl) or an additional cost, that choice is also copied.
No other card is named in this ruling.