D&D 5E Using booming blade on a reaction attack with sanctuary question

[ECMO3]

I have a tempest cleric with booming blade and warcaster. Some question came up on when the booming blade movement damage takes effect.

So I attack an enemy with booming blade. I hit, then I cast sanctuary on myself. The enemy tries to move on his turn and I use a reaction to attack him with booming blade again. What is the sequence everything happens. This is important, because once I attack him with my reaction that breaks sanctuary and he probably is going to attack me.

Here is how I think this sequence occurs. Enemy is sheathed in booming energy to start his turn and right next to me.

Enemies Turn:
1. Enemy moves out of my reach
2. takes booming blade movement damage
3. triggers AOO
4. Reaction Booming blade AOO hits for normal (non-movement) damage
5. Sanctuary drops
6. He is now 5 feet away and sheathed in booming energy again so if he moves back and attacks me he takes booming blade movement damage again. Of course if he has a 10 foot reach he can just attack me from where he is.

Is this the correct order of things?

 

[Krachek]

Why is he five feet away?
Once you attack him with your AOO he can stay there and attack you back.

 

[Bayushi_seikuro]

Here's my read:
First, remember, you don't have to take your AoO just because it's available.

If you choose to take an attack while under Sanctuary, once the attack action is completed, Sanctuary would drop ("If the warded creature makes an attack, casts a spell that affects an enemy, or deals damage to another creature, this spell ends.") It would drop even if you had a way to do a spell attack for damage, not just a melee attack.

But, the opponent moving 5'+ would take the booming damage as well if they willingly moved. So, I'd say the net effect is - you could do your AoO or not, Sanctuary should still drop either from AoO damage or from your Booming Blade spell doing damage to him when he moves, I would thing.

 

[ECMO3]

Why is he five feet away?
Once you attack him with your AOO he can stay there and attack you back.

He moved out of my reach causing an AOO and my reach is 5 feet:

"You can make an opportunity Attack when a Hostile creature that you can see moves out of your reach."

So if my reach is 5 feet he needs to move outside of that to trigger the AOO (and trigger the booming blade damage). Am I reading this wrong?

 

[ECMO3]

Here's my read:
First, remember, you don't have to take your AoO just because it's available.

If you choose to take an attack while under Sanctuary, once the attack action is completed, Sanctuary would drop ("If the warded creature makes an attack, casts a spell that affects an enemy, or deals damage to another creature, this spell ends.") It would drop even if you had a way to do a spell attack for damage, not just a melee attack.

But, the opponent moving 5'+ would take the booming damage as well if they willingly moved. So, I'd say the net effect is - you could do your AoO or not, Sanctuary should still drop either from AoO damage or from your Booming Blade spell doing damage to him when he moves, I would thing.

Good point. I guess this is the order then:

Enemies Turn:
1. Enemy moves out of my reach (5 feet)
2. takes booming blade movement damage
3. Sanctuary drops
4. triggers AOO
5. Reaction Booming blade AOO hits for normal (non-movement) damage
6. He is now 5 feet away and sheathed in booming energy again so if he moves back and attacks me he takes booming blade movement damage again. Of course if he has a 10 foot reach he can just attack me from where he is.

Is this the correct?

This also brings up another option for the enemy, he could move sideways, staying within reach and trigger the booming blade damage and drop sanctuary without triggering an AOO.

 

[Maxperson]

He moved out of my reach causing an AOO and my reach is 5 feet:

"You can make an opportunity Attack when a Hostile creature that you can see moves out of your reach."

So if my reach is 5 feet he needs to move outside of that to trigger the AOO (and trigger the booming blade damage). Am I reading this wrong?

You're reading is correct. As soon as you attack with your reaction, the Sanctuary will drop and he is 5 feet away or further if he was moving more. The AOO doesn't trigger until he moves out of your reach by a method that triggers AOO.

 

[Krachek]

He moved out of my reach causing an AOO and my reach is 5 feet:

"You can make an opportunity Attack when a Hostile creature that you can see moves out of your reach."

So if my reach is 5 feet he needs to move outside of that to trigger the AOO (and trigger the booming blade damage). Am I reading this wrong?

When you make your attack the monster is obviously within your reach, so he has not move yet.
if he continue moving he will trigger the booming blade, but since your sanctuary has drop down, he may stay there and attack you instead.
The monster trick you!

 

[ECMO3]

When you make your attack the monster is obviously within your reach, so he has not move yet.

This is contrary to what the rules say. You can't make an opportunity attack against an enemy that is within your reach. If he triggered the AOO then he must be outside your reach. The fact that you can make an attack against an enemy beyond your reach is a case of specific rule for AOOs vs general rule for attacks.

 

[Charlaquin]

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.

Bold added for emphasis.

Since the attack occurs before the creature leaves your reach, I would rule that the sequence goes:

1. The enemy begins to move out of your reach
1a. Right before the enemy moves out of your reach, you make an opportunity attack
1b. Sanctuary ends due to you making an attack
2. The enemy finishes its movement
3. The enemy takes damage from Booming Blade

If your DM rules that you can cast Booming Blade instead of making an attack when the enemy provokes an opportunity attack from you (which is not normally possible), and you hit with it, the enemy would theoretically take the damage from both instances of the spell.

 

[Charlaquin]

This is contrary to what the rules say. You can't make an opportunity attack against an enemy that is within your reach. If he triggered the AOO then he must be outside your reach. The fact that you can make an attack against an enemy beyond your reach is a case of specific rule for AOOs vs general rule for attacks.

Incorrect. The rules explicitly state that the attack occurs right before the creature leaves your reach.