User blog comment:Canvasofgrey/A New View on Supports v.1.1/@comment-96.30.138.69-20120421024840

I urge you to move away from support transitioning to AP builds. AP items are very expensive and by end game you will be very weak for an AP character in terms of both damage and survivability. If you just build pure support (adding rylai's for added utility depending on the character and maybe a kage's/dfg if you're doing really well), you'll still be weak for an AP character, but you become surprisingly resiliant.

This throws a lot of people off, espeically if you're playing a character who is usually a high priority target like Cassiopeia. There are few exceptions, but generally when you're playing support you really should focus on building support. Being a strong support is more important than being a mediocre (if you're lucky) AP character. Otherwise you might as well play mid.