Karn, Legacy Reforged's power and toughness are each equal to the greatest mana value among artifacts you control. At the beginning of your upkeep, add {C} for each artifact you control. This mana can't be spent to cast nonartifact spells. Until end of turn, you don't lose this mana as steps and phases end.
![Karn, Legacy Reforged (Future Sight) [Mystery Booster 2]](http://www.cardmerchanttakapuna.co.nz/cdn/shop/files/87a05d0f-8e30-5dcd-ac9e-64b1a027a686.png?v=1737252730&width=1445)