Mo'arg Artificer + Bloodmage Thalnos bug

When an enemy has three Mo’arg Artificers and Bloodmage Thalnos on his board and you use mage’s spell “Combustion” on one of the Mo’arg Artificers, the spell kills only one minion.
Here’s the video: https://www.youtube.com/watch?v=sBRp6xynOI4

its working as intended. moarg just adjusts the damage it takes when somethign takes damage. combustion will look at moarg and see that it will need to use 4 damage to kill it, it will also conclude that it wont deal damage to anything else because all its damage needs to be allocated to the targeted moarg. it then deals the allocated 4 damage to moarg, the 3 moargs then double that damage dealt to the single target

Why then Combustion works fine and kills all three moargs without Thalnos on board??? You can try it yourself

??
thalnos is giving your opponent spellpower. why should it affect your combustion?

Unless there are other factors at play that you overlooked, that would be a bug. Please provide a screenshot, video recording, or hsreplay link, so that Blizzard can investigate the exact circumstances that cause this to happen.