As it currently stand in the game, when one of the offensive aura is triggered, the heroes that are linked in the aura will attack the monster that triggered the aura and apply the debuff/cc to that monster only. If the monster die during the process, then the triggered heroes will do nothing.
This is pretty clunky considering auras play such an important role in battles and it's even worse when you have more than one heroes linked to an offensive aura:
1. You can have "When hero attack/crit, there is a % chance to trigger others in aura to attack with % of their attack" activated during attack phase only to have the monster die on the initial attack and have the trigger attack(s) go to waste, losing a chunk of your DPT.
2. If you have "When hero attack/crit, there is a % chance to trigger others in aura to poison/stun/silence/sleep for x turn(s)" aura that are linked more than one heroes being activated during attack phase, the triggered heroes will only apply the debuff to the monster that triggered the aura - and since debuffs cannot be stacked, only one hero is needed for this aura and it makes the 2nd and 3rd heroes linked to the aura useless.
In this game auras play an important role in battle, but due to this offensive auras are much inferior than healing/buff auras where all of the heroes linked to the aura get the benefit regardless. My suggestion to this problem is either:
1. Have the heroes linked to aura attack/debuff a random monster when triggered, instead of just the one that started it. This way, even if the monster that triggered the aura dies prematurely, you don't lose the aura damage/debuff.
2. Make the debuffs stackable in duration, instead of having the 2nd and 3rd heroes linked in the aura's debuff be ignored. So the more heroes you have linked to the debuff aura, the longer the debuff duration. This way, there is an actual reason to link multiple heroes to a debuff aura than just one to do the job.