Saiai Kinuhata's (A Certain Magical Index) Offense Armor super-compresses nitrogen around her to act as armor, blocking attacks and drastically increases her strength.
Kenpachi Zaraki (Bleach) compressing his immense spiritual pressure to act as an armor of sorts, similar to Hierro. Even Ichigo's hands got injured in a backlash without harming Zaraki.
Ichigo Kurosaki's (Bleach) Bankai, Tensa Zangetsu compresses his powers into the blade, increasing his strength, durability and speed to tremendous levels...
...and using Blut Vene to compress spiritual pressure into his bloodstream, drastically increasing his defensive powers and sealing wounds shut.
Genryūsai Shigekuni Yamamoto's (Bleach) Zanka no Tachi compresses all the flames into the blade, vastly increasing the offensive and defensive power to absolute levels.
Byakuya Kuchiki (Bleach) compressing his Senbonzakura Kageyoshi petal shards into full-sized swords, raising their offensive powers drastically...
...using Senkei: Senbonzakura Kageyoshi to compress his innumerable petal shards into swords for sharper and more powerful slashes...
...and Shūkei: Hakuteiken
to compress absolutely every one of his blade shards into a single sword of immense Cutting
Nnoitra Gilga (Bleach) using Hierro to condense his spiritual energy onto his skin, turning it iron hard. Due to his spiritual power levels, he claims that his Hierro is the hardest of all users in history.
Using the Quicksword technique, Irene (Claymore) compresses all of her yoki into her arm before unleashing a barrage of sword swings with such great velocity that it is impossible to see with the naked eye.
When fully synchronized with her Innocence, Lenalee Lee's (D.Gray man) power condenses into her Dark Boots, meshing them into a morass of blades, carrying an extremely high weight.
Using the Penetrate! technique, Son Goku (Dragon Ball) compresses all of his ki into his fist enabling him to punch a gaping hole clean through King Piccolo's chest...
...and goes further by compressing his ki into his index finger, enabling him to block Trunks' sword strikes with no ill effect...
...and while using the Completed Super Saiyan Blue state, he concentrates and compresses the overflowing power of Super Saiyan Blue within his own body, allowing him to use the state to its full potential.
Piccolo (Dragon Ball Z) compressing his ki into his fingertips, amplifying his power level by more than three times, and then firing it off as his deadly attack, Makankosappo.
Son Gohan (Dragon Ball Z) compresses his ki into his fist, enabling him to punch through the thick armor of a Cyclopian Guard.
Omega Shenron (Dragon Ball GT) compresses his Negative Karma Ball into a sphere the size of his torso, creating an energy ball powerful enough to destroy the Earth.
Super 17 (Dragon Ball GT) greatly bulks up while absorbing energy attacks, but returns to his normal state by compacting his muscle mass into usable ki.
Goku Black (Dragon Ball Super) compresses his aura into his hand to form an energy blade
to impale Vegeta.
Inuyasha's (InuYasha) Iron Reaver Soul Stealer attack condenses his demonic energy into his claws, greatly increasing their strength and cutting power.
Using the Spirit Gun, Yusuke Urameshi (Yu Yu Hakusho) focuses his spirit energy into his fingertip and then fires it out as a bullet.
Kibano (Yu Yu Hakusho) compresses energy from his environment into his arm, expanding his arm muscles.
The Guyver (Guyver) compresses gravity between its palms to create the Pressure Cannon, a destructive ball of gravity waves.
Rias Gremory (High School DxD) in the process of compressing her Power of Destruction into a ball.
Nanoha Takamachi (Magical Girl Lyrical Nanoha) gathers and compresses stray mana in the area into a large spear, then fires it as a large beam, the Starlight Breaker.
Ian (Marchen Awakens Romance) compresses his magical power and releases it as a powerful beam.
Gaara (Naruto) compressing the selected hardest minerals within sand and chakra into his most unbreakable defense, Absolutely Hard Defense: Shield of Shukaku....
...and again compressing the selected hardest minerals within sand and chakra to into a defense piercing Absolutely Hard Attack: Spear of Shukaku.
Tsunade (Naruto) compressing all of her raw strength and chakra, and then concentrating it all into a single body part for destructive effects.
Sakura Haruno (Naruto) compressing all of her chakra, and then concentrating it all with minute control into her fist for her destructive Cherry Blossom Impact.
While using Sage Mode, Naruto Uzumaki (Naruto) can draw and focuse Natural Energy into his own body, drastically heightening all of his strength, speed, durability, perception and techniques' powers.
After compressing his Tailed Beast Ball, Kurama/Nine-Tails (Naruto) projects it from his mouth as a highly destructive energy beam.
Using his mastery with the powers of the Paw Paw Fruit/Nikyu Nikyu no Mi, Bartholomew Kuma (One Piece) can compress the air itself into deadly shockwave bombs.
Monkey D. Luffy (One Piece) uses Gear Third - Bone Balloon and Busoshoku/Armament Haki - Koka to physically compress his rubbery bones, making them hard like a car tire, increasing his striking and defense powers....
... and Busoshoku/Armament Haki - Koka to compress his spiritual power into his fist, drastically hardening it in both offense and defense.
Vergo (One Piece) uses Busoshoku/Armament Haki - Koka to compress his spiritual power into his entire body, drastically increasing his offense and defense.
Donquixote Doflamingo (One Piece) uses Busoshoku/Armament Haki - Koka to compress his spiritual power into his fist, drastically hardening it in both offense and defense
Pica (One Piece) uses Busoshoku/Armament Haki to compress his spiritual power into his entire body, drastically increasing his offense and defense.
In his Battle Form, Kuyō's (Rosario + Vampire) monster energy is highly concentrated and compressed throughout his body, greatly increasing his strength and combat capabilities.
Tsukune Aono (Rosario + Vampire) compresses his Yōki into his fist to throw a massively powerful punch.
By compressing the power of its Planet Egg, Final Mova (Sonic X) not only generates a gravity field powerful enough to immobilize Super Sonic and Super Shadow but also builds up enough pressure to eventually cause a universe-destroying explosion.
Sadao Maou (The Devil is a Part-Timer!) compresses his magic into his fist, allowing him to land a punch with the force of a nuclear explosion.