Flaming Sphere + Booming Blade

[FrogReaver]

The advantage of FS is the potential of getting the damage twice per round, once with your bonus action and once by forcing them to end their turn next to it or eat thunder. If there is only one target that can potentially yield more damage than SG would give you, but it's rare IME not to be able to catch multiple enemies in your SG aura.

Sure, by all means use spirit guardians when there are multiple enemies you can hit. I'm not suggesting to use this spell in all circumstances instead of it. Same idea with fireball. But, I think we have established that there is a niche for this combo.

 

[Esker]

Some math:

Setting aside the direct damage from your action, since you get that regardless of what you're concentrating on, Flaming Sphere at 3rd level gives you 3d6 save for half out of your bonus action, which figure is worth about 0.8 * 10.5 = 8.4 (60% chance of full damage, 40% chance of half). To get the catch-22 you have to hit with your booming blade attack -- figure 60% chance of that -- which induces the target to stay next to the flaming sphere, for another 8.4. So in total we're getting 8.4+0.6*8.4 = 13.4 average damage from flaming sphere.

Spirit guardians yields 3d8 save for half, which figuring the same chance of a failed save is about 10.8 damage per target. So for that one spell slot, flaming sphere comes out slightly ahead. If there are two enemies, even if we discount the damage to the second one by half, that's 16.2.

But even if there is only one target, Flaming Sphere also constrains your ability to nova, since you are reliant on your bonus action to get that 13.4, so you can't layer spiritual weapon on it. And if you use your action for other spells (inflict wounds, guiding bolt, etc.), you lose the catch-22, which isn't an issue if you're using spirit guardians.

 

[FrogReaver]

Some math:

Setting aside the direct damage from your action, since you get that regardless of what you're concentrating on, Flaming Sphere at 3rd level gives you 3d6 save for half out of your bonus action, which figure is worth about 0.8 * 10.5 = 8.4 (60% chance of full damage, 40% chance of half). To get the catch-22 you have to hit with your booming blade attack -- figure 60% chance of that -- which induces the target to stay next to the flaming sphere, for another 8.4. So in total we're getting 8.4+0.6*8.4 = 13.4 average damage from flaming sphere.

Spirit guardians yields 3d8 save for half, which figuring the same chance of a failed save is about 10.8 damage per target. So for that one spell slot, flaming sphere comes out slightly ahead. If there are two enemies, even if we discount the damage to the second one by half, that's 16.2.

But even if there is only one target, Flaming Sphere also constrains your ability to nova, since you are reliant on your bonus action to get that 13.4, so you can't layer spiritual weapon on it. And if you use your action for other spells (inflict wounds, guiding bolt, etc.), you lose the catch-22, which isn't an issue if you're using spirit guardians.

Curious why you set the chance to fail the save to 80% but the chance to hit to 60% ? Nevermind I misread

 

[Esker]

Curious why you set the chance to fail the save to 80% but the chance to hit to 60% ?

I set both at 60%

 

[FrogReaver]

Some math:

Setting aside the direct damage from your action, since you get that regardless of what you're concentrating on, Flaming Sphere at 3rd level gives you 3d6 save for half out of your bonus action, which figure is worth about 0.8 * 10.5 = 8.4 (60% chance of full damage, 40% chance of half). To get the catch-22 you have to hit with your booming blade attack -- figure 60% chance of that -- which induces the target to stay next to the flaming sphere, for another 8.4. So in total we're getting 8.4+0.6*8.4 = 13.4 average damage from flaming sphere.

Spirit guardians yields 3d8 save for half, which figuring the same chance of a failed save is about 10.8 damage per target. So for that one spell slot, flaming sphere comes out slightly ahead. If there are two enemies, even if we discount the damage to the second one by half, that's 16.2.

But even if there is only one target, Flaming Sphere also constrains your ability to nova, since you are reliant on your bonus action to get that 13.4, so you can't layer spiritual weapon on it. And if you use your action for other spells (inflict wounds, guiding bolt, etc.), you lose the catch-22, which isn't an issue if you're using spirit guardians.

I think you are ignoring OA's which is a detriment to the analysis. You keep on giving mitigating factors that take away from the combo - but seem to be ignoring the most obvious addition to it.

 

[Esker]

I think you are ignoring OA's which is a detriment to the analysis. You keep on giving mitigating factors that take away from the combo - but seem to be ignoring the most obvious addition to it.

I'm not sure how OAs help? Maybe you can explain your thinking. The way I see it, staying in place and taking the flaming sphere damage is the better option for the enemy, even before factoring in OA damage. Once you bring in the OA, it just makes the worse option worse, making the enemy's decision clearer, but not making them take more damage.

 

[Esker]

The one situation I can see where OAs help the case is that if you have two enemies sandwiched between you and the sphere, the threat of an OA gives them a reason to stay where they are and take some flaming sphere damage. In other words, booming blade gives you the potential to punish two enemies for moving away instead of the usual one.

 

[FrogReaver]

I'm not sure how OAs help? Maybe you can explain your thinking. The way I see it, staying in place and taking the flaming sphere damage is the better option for the enemy, even before factoring in OA damage. Once you bring in the OA, it just makes the worse option worse, making the enemy's decision clearer, but not making them take more damage.

By level 9 - Flaming Sphere will do 5d6 save for half = 14 Damage

Booming blade auto damage is 9 (when you hit).

The best case here is to move. Except when OA's are factored in....

OA's scale potentially by the number of allies around an enemy. There are probably 1-2 additional melee allies around a solo enemy. That gives the potential for 2-3 OA's if the enemy tried to move. Thus, making the enemies best option to stay put and take the flaming sphere damage.

 

[Esker]

Thus, making the enemies best option to stay put and take the flaming sphere damage.

Yes, I agree. But I was already assuming that's what they did. So using a 5th level slot, we get:

Flaming Sphere: 14 (BA) + 14*0.6 (end of their turn) = 22.4
Spirit Guardians (one target): 5*4.5*0.8 (start of their turn) = 18

Still better to use SG if there are even 2 targets, even with a 50% discount to secondary target damage, and spiritual weapon still more than makes up the difference vs one target if you are nova-ing (which you can afford to do more often by 9th).

 

[FrogReaver]

Yes, I agree. But I was already assuming that's what they did. So using a 5th level slot, we get:

Flaming Sphere: 14 (BA) + 14*0.6 (end of their turn) = 22.4
Spirit Guardians (one target): 5*4.5*0.8 (start of their turn) = 18

Still better to use SG if there are even 2 targets, even with a 50% discount to secondary target damage, and spiritual weapon still more than makes up the difference vs one target if you are nova-ing (which you can afford to do more often by 9th).

In the flaming sphere case - if they move they take OA's. Leaving those out is a huge issue. You need an additional +.4*(OAdmg)