User blog comment:TheJohns/Finally, a reasonable Darius nerf/@comment-3974211-20130222234419

They made this change so that he doesn't always have his ultimate up in lane. They also lengthened Riven's cooldown for a similar reason. Dying once shouldn't be game over. I'm on board with this. I've never personally had an issue against him - but I've played against Riven and I've paid attention over the last year. He's frustrating - not overpowered.

I was aware the timer was 12 seconds, and the multi-kill timer is 10 seconds (I believe).