So when you spin around a titan, and yo-yo to gain speed, followed by an overdrive- would you call that yo-yoing or a spiral strike? Anyway, I decided to try to learn this technique and found out something. I'm not sure if you guys knew this already or if it's a bug, but anyway it seems like you don't even have to time your slash when you reel in. I found that if you hook the nape as perfect as possible, JUST below the hairline in the center, (this also appears to be more effective the faster your speed is) when you reel in you can just hold down attack. It will then overdrive for about a second when it hits the neck, then the attack automatically releases on its own. It doesn't seem to affect damage output, as I was still able to pull off 2-3ks while doing this.
I actually broke my record testing this out heh:http://i.imgur.com/tJkz9Jf.jpg http://i.imgur.com/gw32Po7.png