With the Construct mod's card "Chain Strike", which plays another attack card from your draw pile after itself, the game can attempt to play a card after one's turn has ended (because Chain Strike's damage activates the Nightmare's end of turn), crashing the game. I'm not 100% sure if this is a problem with Chain Strike or with the Nightmare, but given that Chain Strike doesn't cause a crash when stopped from playing another card by the Time Eater I'm going to guess that it's the Nightmare.
With the Construct mod's card "Chain Strike", which plays another attack card from your draw pile after itself, the game can attempt to play a card after one's turn has ended (because Chain Strike's damage activates the Nightmare's end of turn), crashing the game. I'm not 100% sure if this is a problem with Chain Strike or with the Nightmare, but given that Chain Strike doesn't cause a crash when stopped from playing another card by the Time Eater I'm going to guess that it's the Nightmare.