The worst feeling in the world.
When you are at the beginning of a tier/division and you win a game and then you start getting an icredible streak of THOSE games. Yeah, THOSE. The ones where after 3 minutes in the match: "an ally has been slain", and then another one, and then another one, and then another one. And they get free dragons, free turrets, and you just find yourself unable to do anything but watch it happen. They are just all too strong. You can do nothing. Even before you finished farming your lane/the jungle, it is already over. Everyone in your team is 0-3. And you can just watch it happen.
And when that game is over you have 0 LP and one question in your mind: "Should I even try anymore? Should I risk having to re-do the super hard promos because I get demoted? Or should I just wait for the season end while I'm still Silver/Gold/Platinum/Diamond?"
It is the worst feeling in the world for me. I don't know. When it happens I question if it's even worth playing this game, if it's even worth the stress, the practice, the work.