My body consists only one atom. (Check my grammar, please)

I've made the similar cannon with Omega-decay technology, which causes every atom in your body separates to quarks.

I fire my cannon at the next user, who does not have time to dodge the shot.

I throw some random stranger in front of me.

I take your cannon and fire it point-blank at the next user.

I am an extremely hot blob of quark-gluon plasma, which is unaffected by the cannon.

I fly into the next user, instantly vaporizing them and breaking them down into quarks, which I then use make more quark-gluon plasma.

I am part of you.

The next user is split in half

Luckily I am a worm, and thusly have multiple hearts.

Suddenly, the next user is accosted by deadly waffles!

Capture him with Pokeball (?!?) and throw the ball to the lava chamber (wait!)

The next user is reciprocal of zero.

I am infinite! I rule the world!

The next user is the antimatter version of me (infinite) and collide, creating infinite minus infinite, which is a paradox.