Firebending Fire Lord Zuko shows us how fire can be used as energy, as it comes from the breath, not the muscle of direct damage or firebreathing
For example, Charizard ex will be a Darkness card with Fire attack costs and a Grass Weakness (in the TCG, Darkness types are weak to Grass to represent Bug)
Players can immediately negate and destroy said card, but opponents also get a free draw
The infamous planeswalker Tezzeret returns, not as a villains lackey, but as a rogue space captain with his own agenda
Don't confuse these with a set's SEC (Secret Rare) chase cards, though: those are usually separate Character-type printings of a popular character, not alternate versions of that character's Leader card
Your opponent can still destroy the Sword itself with any number of artifact destruction abilities, but artifact removal is relatively rare and can be played around easily