Aura of Evasion

"Stay together," you shout, and intone the words of this spell, casting the crushed gemstone in the air at its conclusion. You are all bathed in a silver-green nimbus of light.

You and all creatures within 10 feet of you gain evasion, but only against breath weapons for 10 minutes. (If a breath weapon would normally allow a Dexterity saving throw for half damage, a creature that was within the aura of evasion that successfully saves takes no damage instead and half damage on a success.) Creatures within the spell's area that already have evasion get  advantage on Dexterity saving throws against breath weapons.