With given info -You get Mage (Able to upgrade equipment) -It increases your stats (All stats) -You can use Inferno and Aqua
Level 3 Castle: 10 Bill to upgrade, unlocks mage. Requirements: 12 Highlands and level 2 castle Level 2 Castle: 4 Bill to upgrade, unlocks Alchemist. Requirements: 25 Lowlands Good enough?
Stats given: 20k/20k/5k/5k Unlockables: Mage (enchant equipment with required minerals). Level 3 castle badge, no bonuses. Price: 10 billion gold