I am thinking about a wizard who has a rat familiar (from the find familiar spell), and has the misty step spell prepared. Can he use his familiar's senses to teleport into another room (where the familiar is hiding) by looking through the eyes of the rat and casting misty step?
The wizard could use his action to switch to the familiar's senses and then use his bonus action to cast the spell. This would greatly reduce the "blind and deaf" time he experiences from doing this.
Best Answer
Yes, you can teleport to somewhere your familiar sees provided that you are currently seeing through it's eyes.
From the Find Familiar spell:
If you've taken the action to see through your familiar's eyes, and then cast Misty Step, then yes, you can teleport to somewhere your familiar can see, provided that it's not more than 30' from your current location.