Fiery Confluence seems sweet, given how flexible it is as a red burn spell. Orim's Thunder Is similar to Fiery Confluence, but lets you hit enchantments. It's not red though, so you wouldn't gain any life. Aftershock just turns into 4 mana destroy target creature, artifact, or land. Flame Rift, Sizzle, Price of Progress, etc just do a ton of damage and gain you a lot of life.
These are just some ideas off the top of my head, but they seem good to me.
Orim's Thunder Is similar to Fiery Confluence, but lets you hit enchantments. It's not red though, so you wouldn't gain any life.
Aftershock just turns into 4 mana destroy target creature, artifact, or land.
Flame Rift, Sizzle, Price of Progress, etc just do a ton of damage and gain you a lot of life.
These are just some ideas off the top of my head, but they seem good to me.
Edit: Righteous Confluence is also sweet.