I just got Sylas and tried him out in a couple custom games with my friend to test his interactions, and find a build I like. I found out stealing Ashe ult is totally busted, once I even stole it from her and just one-shot her right away with it. Also I found out big Sylas is hot.
I tried out Grasp, and that felt awful even though it said it did a lot in the post-game stats. Then I tried Phase Rush, and that felt AWESOME, but I don't know how useful it actually was, and how much of that was my changed basic runes.
What keystone do you like taking, and why?