To cast a spell from your hand, you check it's level first. The level for a spell is in the upper left corner of the card.
You pay a spell's cost by tapping cards in your mana zone for mana. If you are unable to pay for the cost of it, you can't cast the spell.
Game Terms
Game Zones
Characteristics
Card ● Card Abilities ● Card Frame ● Card Name ● Card Rarity
Civilization ● Flavor Text ● Level ● Power ● Race
Civilization ● Flavor Text ● Level ● Power ● Race
Advanced Gameplay