Events

Army Discount Events
From the 2016 Christmas Update on, there have been several events in which players can train troops or brew spells at 10% of the normal cost for a limited time, or 50% for multi-troop events. The troop events function like mini-achievements, in which players need to win three multiplayer battles, each with a certain number of the said troops, to claim 300 Experience and 30 Gems (the Baby Dragon Event gives only 100 Experience, while the GoWiWi Event gives 300 Experience and 20 Gems for Wizard and Witch separately), while the spell events are simply discounts.

Using the exact number of the said troops is not required; it's totally OK to use more than the number of the required troops, as long as at least one star is achieved. The troops in the Clan Castle also count for the number of troops, and are essential for players with lower Town Hall levels that can't train the said troops by themselves. If the Town Hall level is low enough such that neither training nor requesting the said troop is possible, a number will still be displayed, but the mini-achievement reward is unattainable (it's not beneficial to rush buildings). Also, players can aim for this reward and the Star Bonus simultaneously.

For multi-troop events, the reward for each troop is achieved separately, but players can aim for them simultaneously. The requirement for each individual troop is equal to the requirement of that troop's single troop event.

Below is a table about how many troops are needed in each type of event. For most troop events (the first Dragon event is the only exception so far), players need to have at least one fifth of total Army Camp space possible at the Town Hall level being that troop, the number of troops required are rounded to the nearest integer. If the Town Hall level is not enough to unlock the said troop, the requirement becomes filling as many as possible to the maximum level of Clan Castle at the Town Hall level.

*Only available as Clan Castle troops.

The Town Hall level might be the sole factor of the troop requirement, regardless of whether or not the Barracks or Dark Barracks (to unlock the said troop), Army Camps and the Clan Castle are at the maximum level possible at the TH level. For example:
 * A new TH 9 with two level 4 Dark Barracks still requires 4 Witches for the Witch Event, and is therefore locked outside of the reward. Had his Town Hall's upgrade not finished during the event, he would have been able to claim the reward by using two Witches as Clan Castle troops. Same goes for the Witch part of a multi-troop event.
 * A new TH 10 with four level 7 Army Camps requires 10 Balloons rather than 9 for the Balloon Event.

In all these events, players get a chance to gain some resources by queuing just before the end of the event and unqueuing after the event ends. Among these Events, the Dragon Event yields the maximum amount of Elixir possible (993,600 ) and the Witch Event yields the maximum amount of Dark Elixir possible (16,200 ). For multi-troop events, players can also choose to get a mix of both resources.

Note that the figures in the upcoming events are estimates and are probably different from the exact value.

Hog Rider Events
*This cost applies to level 6 Hog Riders in the first Hog Rider Event, as level 7 Hog Riders were only available by gemming during the first Hog Rider Event.
 * From: UTC 10:00 20/12/16 To: UTC 10:00 22/12/16
 * From: UTC 7:00 8/4/17 To: UTC 7:00 10/4/17
 * Maximum resources attainable by queuing and unqueuing: 9,888 (*7,776 )

Dragon Events
*Town Hall 9 needed 3 Dragons and Town Hall 10-11 need 4 Dragons in the first Dragon Event, which is an exception to the table.
 * From: UTC 8:00 7/1/17 To: UTC 8:00 9/1/17
 * From: UTC 8:00 1/4/17 To: UTC 8:00 3/4/17
 * Maximum resources attainable by queuing and unqueuing: 993,600 

Golem Event

 * From: UTC 8:00 14/1/17 To: UTC 8:00 16/1/17
 * Maximum resources attainable by queuing and unqueuing: 11,872 

Jump Spell Event

 * From: UTC 8:00 17/1/17 To: UTC 8:00 20/1/17
 * Maximum resources attainable by queuing and unqueuing: 306,900 

Wizard Event

 * From: UTC 8:00 21/1/17 To: UTC 8:00 23/1/17
 * Maximum resources attainable by queuing and unqueuing: 486,000 

Earthquake Spell Event

 * From: UTC 8:00 24/1/17 To: UTC 8:00 27/1/17
 * Maximum resources attainable by queuing and unqueuing: 3,564 

Witch Event

 * From: UTC 8:00 28/1/17 To: UTC 8:00 30/1/17
 * Maximum resources attainable by queuing and unqueuing: 16,200 

Healing Spell Event

 * From: UTC 8:00 31/1/17 To: UTC 8:00 3/2/17
 * Maximum resources attainable by queuing and unqueuing: 237,600 

Balloon Event

 * From: UTC 8:00 4/2/17 To: UTC 8:00 6/2/17
 * Maximum resources attainable by queuing and unqueuing: 432,000 

P.E.K.K.A Event

 * From: UTC 8:00 11/2/17 To: UTC 8:00 13/2/17
 * Maximum resources attainable by queuing and unqueuing: 769,500 

Haste Spell Event

 * From: UTC 8:00 14/2/17 To: UTC 8:00 17/2/17
 * Maximum resources attainable by queuing and unqueuing: 1,870 

Healer Event

 * From: UTC 8:00 18/2/17 To: UTC 8:00 20/2/17
 * Maximum resources attainable by queuing and unqueuing: 306,000 

Rage Spell Event

 * From: UTC 8:00 21/2/17 To: UTC 8:00 24/2/17
 * Maximum resources attainable by queuing and unqueuing: 326,700 

Baby Dragon Event
This Event only gave 100 Experience rather than 300.
 * From: UTC 8:00 25/2/17 To: UTC 8:00 27/2/17
 * Maximum resources attainable by queuing and unqueuing: 820,800 

Poison Spell Event

 * From: UTC 8:00 28/2/17 To: UTC 8:00 3/3/17
 * Maximum resources attainable by queuing and unqueuing: 3,058 

GoWiWi Event
This Event gave 300 Experience and 20 Gems for Wizard and Witch separately.
 * From: UTC 8:00 3/3/17 To: UTC 8:00 7/3/17
 * Maximum resources attainable by queuing and unqueuing: 270,000 or 9,000 

Valkyrie Event

 * From: UTC 8:00 11/3/17 To: UTC 8:00 13/3/17
 * Maximum resources attainable by queuing and unqueuing: 10,260 

Clone Spell Event

 * From: UTC 8:00 14/3/17 To: UTC 8:00 17/3/17
 * Maximum resources attainable by queuing and unqueuing: 198,000 

Minion Event

 * From: UTC 8:00 18/3/17 To: UTC 8:00 20/3/17
 * Maximum resources attainable by queuing and unqueuing: 2,400 

Lightning Spell Event

 * From: UTC 8:00 21/3/17 To: UTC 8:00 24/3/17
 * Maximum resources attainable by queuing and unqueuing: 257,400 

Giant Event

 * From: UTC 8:00 25/3/17 To: UTC 8:00 27/3/17
 * Maximum resources attainable by queuing and unqueuing: 345,600 

Skeleton Spell Event

 * From: UTC 7:00 4/4/17 To: UTC 7:00 7/4/17
 * Maximum resources attainable by queuing and unqueuing: 2,772 

Freeze Spell Event

 * From: UTC 7:00 11/4/17 To: UTC 7:00 14/4/17
 * Maximum resources attainable by queuing and unqueuing: 346,500 

Raging Wizards Event

 * From: UTC 7:00 15/4/17 To: UTC 7:00 17/4/17
 * Maximum resources attainable by queuing and unqueuing: 451,500 

One-Gem Collector Boost Events

 * During each annual anniversary of the game (late July to early August), players are able to boost each Gold Mine, Elixir Collector and Dark Elixir Drill for 7 days with 1 gem. Normally, each player can boost each of his collectors for one round, but if they're not at the maximum level, he can choose to press upgrade and cancel and boost for a second round, but will waste half of the upgrade cost (especially for Dark Elixir Drills, which have high upgrade costs).
 * During each Christmas, players are able to boost each Gold Mine, Elixir Collector and Dark Elixir Drill for 1 day with 1 gem, with the maximum number of rounds equal to the number of days in the event.

One-Gem Troop Training Boost Events

 * During each Christmas, players are able to boost each Barracks, Dark Barracks and Hero with 1 gem. However, the gem boost "discount rates" vary in each year's event. A 7-day Valentine Hero boost event also started on UTC 13:00 13/2/17.

One-Gem Spell Brewing Boost Events

 * During each Halloween, players are able to boost the Spell Factory and the Dark Spell Factory with 1 gem. However, the gem boost "discount rates" vary in each year's event.

Clan XP Events

 * From: 9/4/15 To: 16/4/15 (2x)
 * From: 7/4/16 To: 15/4/16 (2x)
 * From: 7/4/17 To: 17/4/17 (3x)
 * Increased Clan XP can be awarded if the endpoint of a war lies in the interval of an event.
 * These Events are celebrating the first through third anniversaries of Clan Wars, respectively. Each Clan was able to fight at most four, five and six wars respectively with increased Clan XP in the three events, due to the 23-hour Preparation Day.

Star Bonus Events

 * From: UTC 8:00 10/1/17 To: UTC 8:00 13/1/17 (2x)
 * From: UTC 8:00 7/2/17 To: UTC 8:00 10/2/17 (4x)
 * From: UTC 8:00 7/3/17 To: UTC 8:00 10/3/17 (2x)
 * From: UTC 8:00 28/3/17 To: UTC 8:00 31/3/17 (2x)
 * During the Star Bonus events, the Star Bonuses are multiplied by a factor. Players are able to get a maximum of 4 increased Star Bonuses during each 3-day event, probably having to waste some "Star Bonus Time", but still beneficial to do so.

Santa's Surprise Event

 * From: UTC 10:00 23/12/16 To: UTC 10:00 6/1/17
 * It was the first of three "Clashmas" gifts. See Santa's Surprise page for more information.

Freeze Trap Event

 * From: UTC 10:00 27/12/16 To: UTC 10:00 6/1/17
 * It was the second of three "Clashmas" gifts. See Freeze Trap page for more information.

Ice Wizard Event

 * From: UTC 10:00 30/12/16 To: UTC 10:00 6/1/17
 * It was the third of three "Clashmas" gifts. See Ice Wizard page for more information. Also, there was a mini-achievement during this time period. Players needed to win three multiplayer battles, each with a certain number of Ice Wizards, to claim 300 Experience and 30 Gems.

Trivia

 * From the first Dragon Event on, there's a troop event that starts on UTC 8:00 every Saturday which lasts two days and yields Experience and Gems, and a non-troop event that starts on UTC 8:00 every Tuesday which lasts three days, and moved to 7:00 due to Daylight Saving Time. Each of these events is announced in the Events tab one hour before the beginning of its predecessor. Exceptions are the extended multi-troop events scheduled in place of the troop event, which start on Friday and end on Tuesday, filling the two 1-day gaps that normally have no events.