I had a first in ranked a few days back -- someone said in champ select "sorry, just lost my promos, I'm going to feed" and then literally spent all game running straight down various lanes and dying. Ended up 0/13/0 in a 13 minute game with 0 damage to champions. As soon as the game ends, I report and queue up again, and *guess who's on the enemy team, doing precisely the same thing!* Alright, fine, I'll report, they'll be punished, everything's good. Surely two games in a row of everyone reporting clearly punishable behavior will do it, right?
Except... they're still playing ranked games, several a day, since then.
How many times can you intentionally feed before being banned? I'm astonished the number is more than 0, honestly.
According to the boards "naming and shaming" is against the rules so I'll withhold the match history links, but they indicate *pretty unambiguous* behavior.