Destruction Domain: Clerics who find everything a battlefield.

[noob]

The Aura CAN add +30 damage... If you have at least six allies, and all of them hit with at least one attack before your next turn. Which doesn't feel super likely to me, in most normal-sized games.

I dunno, I feel like it's something I'd almost never use due to action economy. If your table rolls differently, it can work for you, but to me? Not a very appealing feature.

It applies to damage rolls.
So if you somehow find a way to deal damage other than by hitting a single target it is much better.
Ex: two the members of the team have shatter and use it at once to try to kill three targets close to each other: on their own they will dea a total of +30 damage(+10 to each target) without you needing 6 allies.
Please note it is still not strong and is situational to allies having a way to deal damage to multiple targets with a single damage roll.
But I think it would be much better if it worked the following way: when you activate it you can make the 6 next damage rolls of allies this turn deal extra damage (so you still get full use without needing 6 allies if your allies have extra attack)
Then at later level make it spend a bonus action or something so that it is still worth it.

It is also extremely powerful if you play with the rule that magic missile rolls damage a single time and applies the roll for all missiles: this way you can boost further a nuclear force missile mage.