Have a replay if needed, but it's pretty straight forward. Oracle's attack beam (when you toggle it on) can attack and dmg your teammate's CC and eventually kill it.

There is a lot of troll using this strategy, please correct it

Honestly I hesitated to put this on the forums for that reason... I'm guessing this is going to be with us for a while though.

I used it to kill a feeding team mate. At the point he rallied his goliath to enemy base.