Major bug concerning Vlad's pool.

Played a ranked match as Vlad against Cho'gath. Everytime I would use Sanguine Pool, he would use his Feral Scream and it would immediately deal regular damage and silence me. According to the tooltip, this should NOT happen. It says that Vlad becomes "untargetable", which is the exact same description for Fizz's E. It is either deceptively inconsistent, or a major bug. It made trading with Cho'gath in lane absolutely impossible because I had an entire ability that was totally worthless.