death message skript %attacker% identify

[main umbra]

soo I'm trying to do 2 things in this death message skript
1 st I need to set death messages which involve an attacker
2 nd natural deaths without an attacker

soo the problem is how can I show the attacker if the victim got killed by lava which placed by the attacker ( but he's not an attacker at all i mean he's not attacking but killing using lava )

Soo i tried the both and the code gives 0 errors