Bosh, Iron Golem is a little lower at eight generic mana, but it has an ability that allows you to sacrifice artifacts to deal damage equal to their mana value to any target
This red creature creates two energy counters when it attacks, so all you need is to create more energy counters alongside it with cards like Aetherworks Marvel and Brotherhood Scribe
If you need a bit more of a push to maximize your convoke triggers, you can play the Invasion of Segovia, which, when it flips to Caetus, Sea Tyrant of Segovia (a very impressive name for a 3/3 creature), it gives all your noncreature spells convoke, letting you bust out some combat tricks when you're normally tapped out
That's something worth holding onto, even if its as ethereal as the feather of a black chocobo
What are they, and what order would you put them in