Three meld cards have been revealed so far for the upcoming set, The Brothers' War - Legendary Artifact The Mightstone and Weakstone and Legendary Human Artificer Urza, Lord Protector
With many formats revolving around 20 life, dealing 10,000 damage is way overkill, and it's most likely there for flavor since Final Fantasy 's Jumbo Cactuar also has an attack called 10,000 Needles that deals that much damage to one party member
This indestructible saga knight creates a ton of tokens over three chapters as it gains lore counters, and then it gives you a massive pump with indestructible counters
You get a chance to add transforming sagas that represent powerful past Avatars, and with all the clues, earthbent lands, and unblockable little spirits running around, you'd think a 100-year war might come to a conclusion