If you could create any jutsu what would it be

[Sanguis]

rinnegan + sharingan 2 on 1 lol.

that would be the Juubi eye:

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On topic: I would have a Jutsu that works like Gaara's sand but has the properties of C4(mini explosives).

 

[Cocytus]

it would be something similar to gaaras techniques, but instead of sand i´d use air itself
like a kekkei genkai that lets you control air and air pressure around you
imagine all the things gaara does but invisible for the normal eye