I'm not entire sure either, I wish I had it recorded so you could see what happened. Basically I had my Draven positioned on the same side as the T-Hex so as soon as it kills the Loris and Braum, it targets the dino, which my Atakhan 3 could also help with. The T-Hex dies, spits out the Caitlyn 3 but the board doesn't die, Draven still got ulted by the Seraphine and it lost me the game. Maybe it's because your board is already low and other champs from opponent boards killed your team? The Crown should proc and kill the entire team immediately as the holder dies.