Liquid flame would look great on non-dragon units, right? And the vulnerability aura also looks cool on units made of magma? The death explosion isn't overpowered, which is why it's not in the final version of the game?
But actually, we could think about the "explosion" idea. Maybe we could remove the unit's shield and give it an explosion instead. What do you think?
Added 2 minutes later
Do you mean the game files from the game mechanics?
We can leave the shield on level 5. With this combination of abilities, we'll get a unit that is just extremely unpleasant to fight in melee combat. It's a very suitable property for a combat machine, in my opinion.