Cards are the only method of deploying troops, spells, and buildings onto the battlefield.
Spells can be cast anywhere in the battlefield, while buildings and troops must be spawned on your territory.
The only exceptions are the Miner, as it drills underground to any point on the map, and The Log, a spell that can only be placed in your territory.
There are 4 levels of card rarity: Common (signified by gray or pale blue), Rare (signified by orange), Epic (signified by purple) and Legendary (signified by a color rainbow).
Also see Rarity.
Each rarity has a different number of levels.
Common cards have 13 different levels.
Rare cards have 11 different levels.
Epic cards have 8 different levels.
Legendary cards have 5 different levels.
Deploying cards costs Elixir, which is gradually gained during battle.
Cards can be obtained through buying them with Gold in the Shop or finding them in assorted Chests.
Chests can always contain cards from Arenas that you have already passed (except the Legendary Chest which contains a Legendary card from any arena).
Unlocking a new arena adds new cards to the Chest rewards - none are taken out.
If you received Chests in a lower Arena, it will only contain cards from that arena and below, even if you advance to a higher arena.
This includes Free Chests and the Crown Chests which contain cards from the arena you earned them in, even if you got the crowns in a lower or higher arena.
Once you have unlocked a Card, you don't have to unlock it ever again. Even if you donate your only copy of a recently unlocked card, you get to use the Card permanently.
Additional cards obtained will fill up an upgrade meter.
Once the meter is full, you can upgrade the card with Gold. Upgrading the card occurs instantly.
If your card has reached the max level, you can hold additional cards (100 for Commons, 10 for Rares, 1 for Epic and Legendary) for donations.
When even this meter is maxed out, each card received will give you a certain amount of Gold. This also holds if you have enough cards to upgrade to the max level but haven't upgraded it yet. For example, when the upgrade meter of a level 10 Common card reaches "8100/1000", each additional card will be converted to 5 Gold.
Every Common over the maximum gives 5 Gold
Every Rare gives 50 Gold
Every Epic gives 1000 Gold
Every Legendary gives 20,000 Gold
Card levels in combat are displayed next to their health bar, with the exception of spells.
However, your cards will not display their levels if undamaged.
That being said, the player's cards do temporarily show their levels while being undamaged if they are under the effect of an enemy spell that deals no damage, such as Freeze.
For cards, all health and damage stats are increased by roughly 10% per level.
Cards that are able to spawn troops, such as the Goblin Hut and Witch will have their spawned troop level increased by 1 per level.
To browse all cards, go here.
Placing cards require a 1 second server delay to place before its deploy timer starts to count down.