Earn chests to unlock earn Gold and Gems, collect new Cards, and upgrade existing cards.
Silver, Golden, Giant, Magical, Epic, Legendary, and Super Magical Chests can be earned by winning battles after the tutorial.
Free and Crown Chests are available periodically, but Crown Chests require earning a certain amount of crowns to unlock.
Tournament Chests are earned by placing in the top 20% of a Tournament.
Challenge Chests are earned by playing in a challenge. The number of cards and gold inside increases with each win in a Challenge.
Clan Chest and Clan Battle Chests are earned by the amount of crowns/wins your Clan collects in a correponding event. The chest tier and its rewards increase with the number of crowns/wins collected, but the cards they contain are affected by your current arena.
Each player has four chest slots, so you can only have up to four (Silver, Gold, Giant, Magical, Super Magical, Epic, or Legendary) chests waiting at a time. It is still possible to battle when your chest slots are full, but no chests will be won, only Gold. Free, Crown, Tournament, Challenge, Clan and Clan Battle Chests do not fill and block these four slots since they are stored elsewhere.
All chests have better rewards at higher Arenas (except Legendary Chests, which contain one legendary card from any Arena).
Chests always contain cards from the Arena the player earned them in and below (except for Legendary Chests, which can contain a Legendary Card from any Arena). Unlocking a new Arena (apart from the Legendary Arena) adds new Cards to the Chest rewards — none are taken out.
Only Free and Crown Chests can contain Gems.
When you earned a Chest, it will contain cards from the Arena you were in and below.
Rarity
Rare Cards are about 10 times rarer than Common Cards.
Epic Cards are about 20 times rarer than Rare Cards and about 200 times rarer than Common Cards.
Legendary Cards are about 20 times rarer than Epic Cards, about 400 times rarer than Rare Cards and about 4000 times rarer than Common Cards. Source
Any chest besides Legendary Chests can contain Epic Cards.
Any chest from P.E.K.K.A's Playhouse (Arena 4) or higher besides Epic Chests can contain a Legendary Card.
Check out our Card Chance Calculator to find out the probability of getting cards of a given rarity in a certain chest.