You can only have a maximum of 3 Creatures on the battlefield at once. When a 4th is ready, you will be prompted to replace one of the three on the battlefield. You may choose NOT TO replace the Creature and the Creature with full mana will continue in your hand ready to be cast. To prevent the "replacing" prompt from appearing you can Disable the auto casting option as follows:
- If you wish to Disable a card so that it doesn't automatically cast once it's 100% filled with Mana, then click on the card's icon. This will darken the icon color, signifying it is Disabled.
