[2019] Just Encountered a Bug on the Online Client

How does someone report bugs on the app?

I was at four health, my opponent at 6.

I had a flesh to stone across from my opponents orruk unit. I played a Frenzied Bloodletting on my Reikenor and used the heroic action of my Crypt Infernal Courtier. As I was about to win, the orruk unit left the field and his Cruisin' for a bruisin' activated and killed me.

Tom (my opponent) do you know what happened?

Edit: Got it, he had a Kunnin' Grot Shaman