Can a multitarget spell with a range of "Touch" be delivered by both a familiar and the caster simultaneously?

Question

I'm a level 5 warlock with Pact of the Chain, so I can cast invisibility with a level 3 slot, and cause 2 creatures to become invisible.

Can I use my familiar to deliver invisibility to both someone who isn't in my range (e.g. 80 feet away from me) and myself with 1 casting?

Answer 1

No (according to the designer's intent)

When asked to answer this question, Jeremy Crawford had the following response on Twitter.

If your familiar delivers a touch spell, you don't also deliver it.

The rest of this answer was written before that response from the designer was available, but I will preserve it for historical reasons and to emphasize the logic behind the "no" ruling.

No (also according to the following reasoning)

The text of the find familiar spell states (emphasis mine)...

...when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it.

There are two key word choices in the emphasized portion above that justify the "no" answer when read idiomatically (or in a straightforward and colloquial fashion as intended by the designers.)

1. "Your familiar can deliver the spell as if it had cast it."

   • If the intention were to allow discrete effects of the spell to be delivered separately by you and by the familiar, then the rules for find familiar ought to use a phrase such as "part of the spell" or "some effects of the spell."
   • Therefore, the rules imply that "the spell" as a whole can be delivered by the familiar.
   • Thus part of the spell cannot be delivered by the familiar while another part is delivered separately by you.

2. "Your familiar can deliver the spell as if it had cast it."

   • There is no other scenario in the entire rules in which one instance of a spell can be cast by two creatures or in which one touch spell's effects originate from two different points.
   • If the intention were to create a specific rule allowing dual casters for a spell or dual points of origin for a touch spell to override the general rules, then the rules for find familiar ought to explicitly define an exception by using proactive phrasing such as "as if it had cast it in addition to you." Since the rules are silent on any such exception, it seems they expect the phrase to be understood within the scope of the general rules wherein a spell has a single caster and a touch spell has a single point of origin.
   • Therefore, if the spell is being delivered as if the familiar had cast it, then it is being delivered as if not you but instead another creature had cast it. Any other reading would imply that the touch spell had been cast by two casters and originated from two points, a scenario that would require an additional exception to be defined.
   • Thus only creatures within touch range of the familiar could be targeted by it.

3. "Your familiar can deliver the spell as if it had cast it."

   • The only exception created is for delivery, not any other aspect of the spell, because the only exception granted by find familiar is that the familiar "can deliver" the spell.
   • If there were any other aspect of the spell that could be changed other than its point of origin, we would expect a phrasing that creates another exemption or which describes the familiar as the caster for all purposes, such as "your familiar can cast the spell" or "your familiar can be treated as one of the casters for any effect of the spell."
   • Since the rules are specific in defining an exception for delivery only, the only aspect of the spell which can be changed is the point of origin. For example, if the familiar were to deliver beast sense then it would still be you, not the familiar, who perceives through the target beast's senses, since you were the actual caster in all but delivery.
   • Thus only the point of origin of the touch spell (an existing property) can be changed, not the quantity of points of origin (a non-existent property for which no exception is made).

Caveat for Rule Zero.

Of course a DM could rule "yes" instead, probably because splitting a spell between you and your familiar could be seen as a fun, cool, or creative use of a familiar. Nevertheless, that ruling would violate rules-as-intended.

Answer 2

Yes

The relevant text is as follows.

Finally, when you Cast a Spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an Attack roll, you use your Attack modifier for the roll.

The key is the phrase "deliver the spell as if it had cast the spell."

A familiar cannot cast spells. It has no spell slots, it knows no spells, and it cannot cast them to begin with. It cannot be counter-spelled, it cannot be targeted by Mage Slayer.

Therefore, it's sole capacity is to deliver touch spells as if it were the source of the spell, as a reaction.

This capacity does not, in any way, limit your own capacity. There is nothing in the rules supporting that; you still cast the spell, and the find familiar wording does not say anything about you. You're still prevented from targeting more creatures than can be targeted per general rules, but nothing more.

Therefore, both you and the familiar act as if they had cast the spell, you because you did and the familiar due to the spell description, and therefore you can deliver it to any target either of you can touch.