A wizard casts Misty Step (2nd level bonus action) to get to an advantageous position, the rules state that if you want to cast another spell with your action this turn it has to be a 1 action cantrip.
The wizard wants to cast silent image though. Can he take the ready action so the spell is cast on the same round but not the same turn?
The rules say that readying a spell requires you to cast it as normal, and when the trigger comes you just release the energy, meaning you have to concentrate until then. I would rule that the spell is thus casted on the same turn, it's release is not, so it would be against the rule.