Does Repelling Blast work once per spell or once per beam?

Question

Warlocks can take the following invocation:

Repelling Blast
Prerequisite: eldritch blast cantrip

When you hit a creature with eldritch blast, you can push the creature up to 10 feet away from you in a straight line.

This could be read as "when you hit a creature with your eldritch blast cantrip", i.e. once per turn regardless of beams/damage, or "whenever a creature gets hit with one of your eldritch blasts", which might happen more than once per turn. Which is correct? Can a Level 5 Warlock push a single goblin back 20' per round if they hit twice? How about two goblins for 10' each?

Answer 1

The Repelling Blast Invocation applies to each hit

Since we know you can select the target of each separate Eldritch Blast ray separately , even to the extent that other Repelling Blasts could actually push the same creature out of range of the remaining subsequent beams, we must rule that Eldritch Blast (no matter what Invocation is attached to it) is a single spell that hits in sequence, not simultaneously as per Magic Missile.

This is further expanded upon when we look at Hex, which triggers each time an attack hits the Hex'd target.

So the only conclusion the sound logic and readings of these rules can give us is that Eldritch Blast, Scorching Ray, and similar spells that require multiple attack rolls to hit their target(s) are NOT simultaneous and always hit independently of each other, in succession, unless otherwise noted in the spell's description.

As you pointed out, the prerequisite for Repelling Blast is:

"...When you hit a creature with eldritch blast..."

Eldritch Blast requires you to determine if you hit or miss each target or targets for each beam (not once per spell), thus letting us know if the requirements 'when you hit' or met or not. Repelling Blast, and any other feature, trait, spell, or spell-like ability that activates when hit or attacked by something would trigger for each Eldritch Blast beam.

So yes, at 5th level with 2 beams you could push a single goblin up to 20ft away, or push 2 different goblins up to 10ft away from you in a straight line. You do not need a separate ruling for hitting the same creature with multiple beams, because your ruling is already included in the spells text.

Answer 2

Each blast takes an attack roll to hit. Per the Eldritch Blast description on p. 237 of the PHB:

You can direct the beams at the same target or at different ones. Make a separate attack roll for each beam.

This question only arose due to only looking at an individual target. If two rays had impacted two different targets, all of us would agree that both targets would be knocked back, correct? So if 2 blasts hit, each would knock back the selected target 10ft.

If they both hit the same target (still requiring 2 separate successful attack rolls), by the same logic as noted above, the target would get knocked back 10ft by one impact, and 10ft by the other. This is alluded to in the Repelling Blast invocation description on p. 111 of PHB:

When you hit a creature with eldritch blast...

[Bold emphasis is mine]

Therefore each blast, if it hits, and the Warlock in question is able to and wishes to use a Repelling Blast effect, would benefit from it.

Answer 3

Each ray Repels, but...

Creatures hit with multiple rays requires a ruling

Repelling Blast (Player's Handbook, 5th ed., p111)

When you hit a creature with eldritch blast, you can push the creature up to 10 feet away from you in a straight line.

Eldritch Blast (p237)

...The spell creates more than one beam when you reach higher levels: two beams at 5th level,three beams at 11th level ,and four beams at 17th level. You can direct the beams at the same target or at different ones. Make a separate attack roll for each beam.

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Originally, I'd come to the conclusion that you can only affect a creature once per casting, by way of the Combining Magical Effects rules (p205). As both @DuctTapeAl and @J.A.Streich pointed out however, the Combining Effects rules are not germane to this question: it's one spell, and instantaneous. Discussion w/@SevenSidedDie underscored the 'when you hit a creature with eldritch blast' section.

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This can be read two ways:

1. Each ray hits separately, and damages separately, so the secondary effects are separate, and cumulative, too. Supporting this, Repelling blast merely says 'when you hit...'

2. Alternately, each ray of an eldritch is part of the same eldritch blast. Though a creature is hit with two rays, it's being hit by both rays simultaneously; eldritch blast is an instantaneous effect. So the 'when' is happening at the same time and the caster only moves the creature up to 10' once.

   Under this reading, two or more creatures each hit by a ray from one EB would each have been hit by EB, each moving 10' as well.

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@KorvinStarmast pointed up a tweet-ruling by Jeremy Crawford:

Yes, Repelling Blast can push a target out of the range of subsequent beams from eldritch blast.

Which is in answer to the question:

If you get 3 attacks with eldritch blast, can the first attack push a target out of range of the next two attacks?

This ruling shows that each Eldritch blast attack is independent and cumulative, as per the first option above.

Answer 4

One need only look up at Lance of Lethargy to see the difference in wording between an invocation that activates per hit of EB or one that activates only once per turn on a hit with EB.

Lance of Lethargy
Prerequisite: eldritch blast cantrip

Once on each of your turns when you hit a creature with your eldritch blast, you can reduce that creature’s speed by 10 feet until the end of your next turn.

Answer 5

RAI = you could rule out or in that each beam is a separate 'spell subeffect' of the spell and thus enable repulsion and each beam can repel the target up to 10 feet. I think each could make sense in a RAI based campaign.

RAW = the rule says , nothing else is written so the rule must be taken only with that word for word text, no assumptions or interpretations. When a spell name is in 'italics' it is considered to be the spell itself not its effect, beams or otherwise.

each creature hit by the Eldritch Blast is repelled up to 10 feet

That wording implies that each creature hit by the spell will be repelled, even if you hit the same creature with two beam it is still hit by one Eldritch Blast spell. The word is Blast, not Beam. So each creature hit by the spell will be repelled only 10 feet

BUT if you target two different creatures then each creatures is effectively hit by an Eldritch Blast spell so each will be repelled

ALSO PHB p205 is very clear on stacking effects of the SAME Spell is not allowed

Combining Magical Effects The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don't combine, however. Instead, the most potent effect—such as the highest bonus—from those castings applies while their durations overlap. For example, if two clerics cast bless on the same target, that character gains the spell’s benefit only once; he or she doesn’t get to roll two bonus dice.

In Conclusion

• RAI you can repell the same creature twice or not, both ruling make sense
• RAW = You cannot repell the same creature twice but YOU CAN repel TWO creatures up to 10 feet each.

Answer 6

Going to be the spoil sport to adjudicate, no, on the multiple Repelling Blasts. I use the Combining Magical Effects rule, PHB 206.

The result of multiple Repelling Blasts hitting a single target is that, even if 4 rays hit in sequence, the duration of the pushback is overlapping, therefore no further effect.

Combining Magical Effects
The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don't combine, however. Instead, the most potent effect—such as the highest bonus—from those castings applies while their durations overlap. For example, if two clerics cast bless on the same target, that character gains the spell’s benefit only once; he or she doesn’t get to roll two bonus dice. (PHB, p. 205)

Answer 7

Usually, should not

Repelling Blast (Player's Handbook, 5th ed., p111)

When you hit a creature with eldritch blast, you can push the creature up to 10 > feet away from you in a straight line.

During instant of "when" target can either be hit by eldritch blast (regardless of the number of hits, since eldritch blast rays all happen in same instant) or not.

If condition "hit" is satisfied during that instant "when" for that creature, you can choose to apply repelling blast effect to that creature.

Otherwise rule would, most likely, clearly state "whenever" or "every time".