No there were no acid rain played. Also not only creatures moved to graveyard but 1 artefact. I had 1 token creature generator card the name of which I don't remember as I don't have it in my collection (she generates 1 token 2/2 each turn and can suc a creature for 5 life). Together with Orion, Master Acrhitect, which I also used for generating new creatures
I didn't observe anything like this afterwards, so might be my lack of experience in the game to recognise what really killed them. But I never played the same combination of cards either