This permanent tries to put the emphasis on
's capability to deal the most damage the fastest, early in the game (that was for the mechanisms)
The thematic fitting is the same as Immolation, i'd say: Immo makes you take a "risk" by having you kill your own creature, that you could possibly have needed later on (for example, to help take down a bone wall or something...). The reward for that risk is a stronger Fire creature, which usually doesn't have much HP either. So, both cards make you take risks in exchange for potentially great damage output, as i see it.
From a more aesthetic point of view, i was thinking of Shard of Bravery when making this one, and Empathic Bond sort of. So i thought, "If there was a
Bond, what would it look like?" and this is the result. It has a double-edged effect like SoB, and directly affects health based on the current state of the game like Empathic Bond.
The upped version's balance, well, i'm not sure either. It requires getting at least a 5 HP lead before even being played, else it will be weaker than the unupped version. And you still have to pay 8 (that's 4 minor phoenixes) to use it. But if you successfully do, you could deal very high spell damage to the enemy, ending the fight possibly twice as fast.