Have you got the predictive keyboard row turned on (the row that shows you guesses for words and the undo/redo button at the bottom of the screen, or just above the software keyboard when not using an external keyboard)?
There are add text and add folder buttons there that do exactly what you want to do. Type your synopsis and tap the “+” button in the predictive text two, and another card is created instantly. So the process is:
+, type, touch, type +, …
A neat trick on iOS in general is that if you hold down the Command key, you see a list of all available keyboard shortcuts - and yes, there are keyboard shortcuts for adding cards, and you can use tab to move from the title to text, so you can do all this without taking your hands off the keyboard as follows: