13 Jul 2018
Mistcaller’s ability won’t affect any nontoken creatures that were cast, including ones cast from unusual zones such as your graveyard.
13 Jul 2018
Mistcaller’s ability doesn’t stop creature tokens from entering the battlefield. It also doesn’t affect creatures that are already on the battlefield.
13 Jul 2018
If Mistcaller enters the battlefield at the same time as other creatures, its ability can’t be activated in time to affect those creatures.