Nina Dowd/The Mighty Endowed (DC Comics) can hypnotize people with her breasts.
Rias Gremory (Highschool DxD) using the Oppai Beam, a beam of red energy from her breasts, to recharge Issei, but at what price.
Mii (Jungle de Ikou) is a fertility spirit who's large breasts represent and contain Earth's life-giving energy.
Kawai Hanabi (Keijo!!!!!!!!) can use her breasts to heal her allies.
Kusakai Mio (Keijo!!!!!!!!) can hypnotize people using her Breast Hypnosis Technique against anyone.
Hououin Sanae (Keijo!!!!!!!!) using Perky Pile Piper a technique that can send her opponents flying a considerable distance away.
Sakashiro Maya (Keijo!!!!!!!!) dueling Kaminashi Nozomi with Heaven and Hell breast strike.
Chifusa's (Manyuu Hikenchou) breasts can absorb the Breast Energy of other women's when she uses the Breast Flow technique on them causing her own to enlarge and become increasingly sensitive and supple, while others women's shrink.
As a Slime, Suu's (Monster Musume) breast have supernatural properties that make them grow in size depending how much water she has absorbed...
... and healing abilities such as breastfeeding Kimihito to help heal his cold.
Sara (MisFits) can involuntary use her hypnotic breasts on any men.
Melona (Queen's Blade) is a "slime swamp witch" with various powers and regenerative properties infused within her breasts milk that she can use for projectile combat and healing.
Ageha Kurono (Rosario+Vampire) using her Oppai Missile special attack.
Maria (Seikon No Qwaser) are known for their "soma", a mystical substance found in their breast milk that empowers all Qwaser to manipulate periodic elements for battle.
Mafuyu Oribe (left) and Tomo Yamanobe (right) (Seikon No Qwaser) are both powerful Maria that assisted their Qwaser in their battles...
...Tomo however has proven to be a far more powerful Maria, due to having more potent Soma than most and having bigger breasts that she can use to her advantage for herself.
Miyuri Tsujidô (Seikon No Qwaser) releases powerful energy blast from her breasts, obliterating anything in her path.
Mammon (Seven Mortal Sins) can produce breast milk that has hypnotic and illusionary properties that she uses to her advantage on anyone.
Raven Hex (Tarot: Witch of the Black Rose) can channel her magic through her breasts to create powerful blast.
Tarot (Tarot: Witch of the Black Rose) has the same sex magic as her sister Raven Hex, thus having the same potential to use her breasts as she does.