Chris it's not always that easy to just say "ward brush against Blitz" as Soraka.
I've never had a problem against Blitz as Soraka when I ward brush.
I'm no pro or anything but it's pretty easy to just ward the brush, stay behind the minions after giving mana, wait 10 secs, repeat, wait it out
--
http://i.imgur.com/TXrOO.gif