Let me re-emphasize.
If the ENEMY BELOW THEM* IS DEAD, how is it supposed to hit THEM**?
*This is the enemy you targeted.
**This is the enemy below the enemy you targeted.
If the enemy below the enemy you targeted is dead when the weapon tries to target them, why would it re-target? It wouldn’t. That’s not how the game is programmed for that weapon. That would require more coding, because they would need to program the game to check for new targets in that instance.
The same thing happens with Infernus. See this thread:
There are a whole bunch of other troops/weapons that possibly act the same way or different, such as Sandrunner, The Deep King, Aquaticus, Mistralus, Frostfire King.
Anything that deals splash damage to multiple enemies. It entirely depends on if those targets are chosen when the ability is cast, or if they’re chosen as each instance casts.