Some cards can limit the level of other cards you play. This can happen with the cards Mana Ritual, Metamorph, and Giant Growth.
Whenever you use the Mana Ritual, the level of the Mana Ritual card will define the maximum level your target card will have during the battle. If you deploy a card with a level lower than the Mana Ritual card, the card will be summoned with its original level.
If you deploy a card with a level higher than the Mana Ritual, the card will be summoned with the same level as the Mana Ritual.
The same rule works for the Giant Growth card.
When you use the Metamorph card, it will copy a random card on the battlefield. The Metamorph level replaces the level of the copied card. This means that the copy will show the same level as the Metamorph card.