I play a Warforged Warlock (Hexblade, Pact of the Tome). I have an owl familiar from the find familiar spell. The owl's carrying capacity equals its Strength score of 3 multiplied by 15 (a total of 45 lbs.), halved to 22 because it's Tiny.
I just received a Bag of Holding (weighs 15 lbs), into which I can fit (3×3×7 feet is less than the 64 sq ft volume, and I don't weigh 500 lbs). I don't need to breathe. All good so far.
According to the descriptions for the Handy Haversack and Portable Hole, the Bag of Holding creates "an extradimensional space" (and not a private demiplane).
Can I communicate with (and see through the eyes of) my familiar when it's carrying me in my Bag of Holding?
Are there any other issues with my idea?
Best Answer
No, you can't
The official ruling1 from Sage Advice Compendium
The unofficial tweet from the rules designer Jeremy Crawford
Because you are in an extradimensional space, you and your familiar is not on the same plane of existence. Therefore, you are infinitely far away from each other. The find familiar spell says that
Because you're not 'within 100 feet' - you're infinitely far away by being in different plane - you cannot communicate with it telepathically and see through your familiar's eyes and hear what it hears2.
However,
you can argue that as long as the bag is opened, you are within 100 feet by direct line from within the bag to your familiar, therefore you can use the ability. I tend to interpret it strictly that the opening does not circumvent the 100 feet requirement, though.
1 It is an official ruling how to interpret the rules as they were designed to be. However, it is only a ruling. The DM has the final say and can choose whether to use the official ruling or not.
2 'Additionally' can mean that the ability to use your familiar senses is a separate ability from the ability to communicate with your familiar, which is restricted to 100 ft. However, both abilities are within one paragraph, so 'additionally' must mean that the first ability restriction applies to the second.