Tryndamere bug that needs to be fixed.

Basicly, was playing tryndamere on Summoner's Rift. I bought Guardian Angel, I would hit Ultimate just as I was about to hit 0 Hp, My ultimate would trigger but so would Guardian angel showing me Die not allowing me to move until Guardian angel would bring me back with so much health and screwing me over. this happened several times. I would like it if this bug was looked at and reviewed :) thank you.