Kronos - Percy Jackson
We all know the tale, Kronos swallowed his children whole, except Zeus, who was hidden and Kronos swallowed a rock. I won't go into the tale about how Zeus saved his siblings - it's a waste of time.
Weapons and Powers:
He can stop time, he can slow it down or speed it up. If you were fighting him, he could freeze you, or slow you down so much he could regain all of his energy.
He can enter your dreams, and you'll become his follower, he'd put evil thoughts in your head, corrupting you and your thoughts, ideas and the way you view things.
Kronos also owns a Scythe -a wheat hacking one-. It's made out of two metals: Tempered Steel and Celestial Bronze, giving it the power to destroy demons as well as mortals.
Kronos can only been found unless he has possessed someone. And do this, the possessed has to have been in the River Styx (making them unable to die unless their Achilles Heel has been hit)
How to Kill:
If he's possessed someone, talk sense into them. Stab them, slash them. Do all that you can within your powers.
Once they've stopped trying to kill you talk to them, force the possessed to regain control over their body.
After step 2, get their Achilles spot and stab them in it.
And you're fine to live.
I know he's scary, It's petrifying. I've seen someone get possessed and killed. It's horrible, what they become...it's not pleasant.
Just have faith, have a group, stay strong and you can win.