"Sigil Tracer" is a 2/2 blue merfolk wizard creature card printed as a rare for the Magic the Gathering expansion set known as "Morningtide." This is one of the cards built around the promotion of the synergy between a tribe of creatures. In this case, Sigil Tracer encourages a player to build a deck around wizards. For the most part, Sigil Tracer seems to be a good card to have in a control deck that has a lot of blue cards. With the right combination of cards, you can do a lot of damage with Sigil Tracer.
The converted mana cost for the Sigil Tracer is three. You will need two blue mana and one colorless mana to bring Sigil Tracer form your hand and onto the battlefield. For what the Sigil Tracer can do, the converted mana cost is well worth it. With the right combination of cards, Sigil Tracer becomes a vital card. This is a good card for any blue control deck.
What does Sigil Tracer do in the first place?
By paying one blue mana and one colorless mana, you tap two untapped wizards you control. Then, you copy a target instant or sorcery spell. You get to choose new targets for the copy.
The ability is a built-in "Twincast." Twincast is a blue instant that does the same exact thing. However, Sigil Tracer has a built-in Twincast ability that can be used over and over again. When this ability is combined with other cards, you can do a number on your opponents.
There are plenty of cards that go good with the ability of the Sigil Tracer. One good combination would be "Time Warp" which costs two blue mana and three colorless mana. It is a sorcery spell reprinted as a mythic rare. When cast, you get to go an extra turn. If you have the mana and the wizards to spare, you can copy Time Warp a few times. Being able to go a few extra turns goes a long way. That will really mess up the momentum of your opponents. By copying Time Warp, you can draw lands and cast spells much faster.
If you have spells such as "Traumatize" and "Archive Trap," you can play them to "mill" your opponents' libraries to death. All you simply need to do is pay the mana and tap the wizards. You can cripple your opponent if you manage to play Traumatize and/or Archive Trap and then copy it. If you play Traumatize and copy it once or twice, you can cripple the library of a target opponent.
In a blue and black deck, you can use "Lich Lord of Unx" to produce the black and blue zombie wizard tokens. Since they are wizards, you can tap them along with paying the mana.
Overall, Sigil Tracer is a good card to have in any blue control deck. With the right sorceries and instant spells on hand, Sigil Tracer becomes devastating.