Whenever the enchanted creature is put into the graveyard from play, move Curse of the Fire Penguin onto a new creature
Both Burning-Tree Emissary and Llanowar Tribe have some additional upsides as well, with Burning-Tree Emissary adding two mana when it comes into play, which means we can cast any number of Burning-Tree Emissaries to up our devotion to green and still have enough mana left over to activate Nykthos, Shrine to Nyx at the end of the chain
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All this combined makes it impossible to make a "bad" Sauron deck since he brings so much value on his own, but we can definitely raise the power ceiling by making an optimized brew
Corpse Explosion: A selective boardwipe for 3 mana at the cost of exiling a body from your graveyard seems like good value to me
It also ended up making it an Elemental typal card, encouraging you to add more Elementals to your deck