A common rule is that creatures generally have power equal to roughly 1000 to 2000 power per level, but this varies at each of the levels. A level one creature can currently have anywhere between 1000 and 3000 power, but with various abilities or drawbacks. For example, Blaze Belcher is a Level 1 creature in the Fire Civilization that has 1000 power but is forced to attack each turn. Gigabolver is a Level 1 creature in the Darkness Civilization that has 3000 power that banishes itself at the end of its attack.
Evolution Creatures at different levels often feature higher than average power due to the requirement of needing a creature to evolve from.
A deck can be seen balanced when it features cards that each have a low level (such as in a Rush deck) or in decks that have a varied mix of level creatures with the proper support for its higher level creatures.
|Cards by Level|
In order to pay for the level of a card, at least 1 card of the same civilization that matches the card that you wish to use must be in your mana zone. To summon a Nature creature that is level 4, it requires you to tap 4 mana, and have at least 1 nature card in your mana zone. The corresponding civilization only needs to appear in your mana zone, it's not required to tap it.
If it's a Multi-civilization card, you must have a card of both civilizations in your mana zone.