Love Sign: Master Spark
Kirisame Marisa's most commonly used and powerful spellcard attack. It appears in almost all of the Touhou series games (PoFV, MoF and the PC-98 games excluded.)
Despite being originally created and used by Kazami Yuuka, Marisa (after "borrowing" it) has made it a trademark spellcard of hers, to the point where one of her theme songs is titled "Love-Colored Master Spark".
This is how Marisa uses it:
There's also Marisa's "Last Word" spellcard, known as "Magicannon: Final Spark", "Dual Spark", used by Yuka, which is two Master Sparks fired at once (one being fired by a projected doppelganger), and Mima's fan-made Twilight Spark, which is usually a dark violet in color and extremely wide. An even stronger version exists in fanworks as "Magicannon: Final Master Spark", but is rarely seen.