You can activate it to turn off a Rakdos player's hellbent abilities, force a player to draw an eighth card before their own cleanup phase so that they need to discard, or interfere with Flubs, the Fool's card replacement mechanic
Its my single favorite Enchanted so far, and I would not be surprised to see it retain a lot of value overtime
When using Iago to challenge an opponent's character, suddenly his zero attack power becomes a five
With all that said, I think we can look at staples and Side Deck choices
Furthermore, this fusion is Level 6, meaning that it is useful for making XYZ monsters with the Fiendsmith archetype's most important cards
Instant Color tag templates(None) Doom Blade Destroy target nonblack creature