Off-Topic

The sharingan in general. At first it was just aided perception and a bonus to Genjutsu... which make sense for an ocular ability. Then they gave it all the abilities of the byakugan, then they made it spit sun hot fire, then they let it teleport people throughout space, then they made it suck things into a vacuum, then they made it give people a purple soul skeleton shield that blocks any attack, then they gave it Inazagi that you mentioned, then they let it make people intangible... and I'm probably forgetting some powers and I'm sure more are going to come.

Tsuki-something from the Fullbring arc has the ability to time travel instantly, alter the past based off of the present, teleport back to the present and take advantage of the changes made, all without creating any type of paradox or time rift.

Aizen's shikai is beast mode unstoppable as well.

-Light Hawk Wings (Tenchi Muyo)- The most broken defense I've seen in fiction. Capable of tanking anything up to a universal level from energy attacks to localized space phenomena such as black holes.

-Gae Bolg (Fate/Stay Night)- Lancer's Noble Phantasm. The weapon ignores cause and effect to always strike a fatal blow at its opponent's heart whenever Lancer desires it.

-Gate of Babylon (Fate/Stay Night)- One of Gilgamesh's Noble Phantasms. Essentially a dimensional gate that holds Gil's "treasury" of every Noble Phantasm he has collected throughout history. Each weapon has various different effects and properties where Gil likes to spam them like arrows and fire them at his foe. Gil used Gate of Babylon to easily defeat Berserker in the UBW arc of Fate who was considered the biggest threat in the Holy Grail War.

-Mystic Eyes of Death Perception (Kara no Kyoukai)- Shiki Ryougi's ability to perceive the "death" of living beings and concepts by seeing them in the form of lines. By cutting these lines with a sharp object like a knife, Shiki is capable of annihilating whatever she cuts, whether it be an inanimate object, a ghost or the concept of distance.

-Kyoka Suigetsu (Bleach)- Aizen's Zanpakutou whose Shikai, Complete Hypnosis, has the ability to manipulate the five senses of his foes to the point where they can be fooled to perceive whatever illusion created by the sword is real and is flawless enough in ability where even the strongest Shinigami are unable to escape its influence, even if they become aware of being under the influence of its effects.
 
-Vector Control (A Certain Magical Index)- Accelerator's esper ability to manipulate the vector values of whatever he comes into contact with giving him vast abilities he can make use of from manipulating an opponent's blood flow when in close contact with them to manipulating wind to fire off as immense blasts or fly to even manipulating the Earth's rotational energy to create powerful kinetic blasts. This control has his body covered in an AIM field which grants him auto-defense against most attacks. Accelerator's proficiency with vector control evolves to the point where he is able to perceive, guard against and cast magic later in the series.
 
-Holy Right (A Certain Magical Index)- Fiama of the Right's ability to gain the abilities of the archangel Michael through a bird's talon on his right shoulder he calls his "third arm." Besides being capable of using any powerful magic that Michael can cast, Holy Right also grants Fiama the nasty abilities to auto-warp to any foe that it considers a threat and even auto-kill whatever it touches without any destructive force.

@Levance: rasengan.. because for SOME REASON.. it seems to beat everybody and everything :p