LoL that fight is ****ed up already. Let's say a purple person get purple deletion. Now you have two options:
1. Let the other purple person run in and get rid of both the debuffs, meaning you have no left for the next time purple deletion happens.
2. Say goodbye to the first purple person as their own debuff will not protect them but at least you will have the second debuff ready for the next purple deletion.
If you have yellow and are targeted by yellow(yellow is an example, can be any colour) you dont die. you basically shield yourself.