This has happened every three or four games I have played in the past week. Opponent attacks one of my creatures, and that -X points just flashed. Loop prevention claims it is kicking in but it does nothing. I have to quit the match to continue.
https://photos.app.goo.gl/TqcRJkDsz9V2ZPRd8 is the link I tried to use with a screenshot.
90% of the finale’s are bugged along with reverberation.
I am not sure what a red spell finale is. I don’t think it’s coming at the very end of the match, as I am often winning! 
Hello guys,
Thank you for the feedback, it’s very important for us!
This issue is now under investigation.
Thank you for our patience,
Marcela.