Completing any of the following tasks will grant in-game XP and Gems, as well as XP in Google Play.

Achievement	How to unlock
Bigger & Better (10 in-game XP / 5 Gems / 500 Google Play XP)	Upgrade Town Hall to level 3.
Bigger & Better II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Upgrade Town Hall to level 5.
Bigger & Better III (1,000 in-game XP / 20 Gems / 2,000 Google Play XP)	Upgrade Town Hall to level 8.
Bigger Coffers (10 in-game XP / 2 Gems / 500 Google Play XP)	Upgrade a Gold Storage to level 2.
Bigger Coffers II (100 in-game XP / 5 Gems / 1,000 Google Play XP)	Upgrade a Gold Storage to level 5.
Bigger Coffers III (1,000 in-game XP / 10 Gems / 1,500 Google Play XP)	Upgrade a Gold Storage to level 10.
Conqueror (10 in-game XP / 5 Gems / 500 Google Play XP)	Win 25 Multiplayer battles.
Conqueror II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Win 250 Multiplayer battles.
Conqueror III (1,000 in-game XP / 20 Gems / 1,500 Google Play XP)	Win 5,000 Multiplayer battles.
Elixir Escapade (10 in-game XP / 5 Gems / 500 Google Play XP)	Steal 20,000 Elixir.
Elixir Escapade II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Steal 1,000,000 Elixir.
Elixir Escapade III (1,000 in-game XP / 20 Gems / 1,500 Google Play XP)	Steal 100,000,000 Elixir.
Empire Builder (10 in-game XP / 5 Gems / 500 Google Play XP)	Rebuild the Clan Castle.
Empire Builder II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Upgrade Clan Castle to level 2.
Empire Builder III (1,000 in-game XP / 20 Gems / 2,000 Google Play XP)	Upgrade Clan Castle to level 4.
Firefighter (50 in-game XP / 100 Gems / 500 Google Play XP)	Destroy 10 Inferno Towers in Multiplayer battles.
Firefighter II (500 in-game XP / 200 Gems / 1,000 Google Play XP)	Destroy 250 Inferno Towers in Multiplayer battles.
Firefighter III (5,000 in-game XP / 1,000 Gems / 2,000 Google Play XP)	Destroy 5,000 Inferno Towers in Multiplayer battles.
Friend in Need (10 in-game XP / 5 Gems / 500 Google Play XP)	Donate 100 Clan Castle capacity worth of reinforcements.
Friend in Need II (100 in-game XP / 25 Gems / 1,000 Google Play XP)	Donate 5,000 Clan Castle capacity worth of reinforcements.
Friend in Need III (1,000 in-game XP / 20 Gems / 2,000 Google Play XP)	Donate 25,000 Clan Castle capacity worth of reinforcements.
Get those Goblins! (10 in-game XP / 5 Gems / 500 Google Play XP)	Win 10 stars on the Campaign Map.
Get those Goblins! II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Win 50 stars on the Campaign Map.
Get those Goblins! III (1,000 in-game XP / 20 Gems / 2,500 Google Play XP)	Win 150 stars on the Campaign Map.
Gold Grab (10 in-game XP / 5 Gems / 500 Google Play XP)	Steal 20,000 Gold.
Gold Grab II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Steal 1,000,000 Gold.
Gold Grab III (1,000 in-game XP / 20 Gems / 1,500 Google Play XP)	Steal 100,000,000 Gold.
Heroic Heist (10 in-game XP / 5 Gems / 500 Google Play XP)	Steal 20,000 Dark Elixir.
Heroic Heist II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Steal 250,000 Dark Elixir.
Heroic Heist III (1,000 in-game XP / 20 Gems / 2,500 Google Play XP)	Steal 1,000,000 Dark Elixir.
Humiliator (10 in-game XP / 5 Gems / 500 Google Play XP)	Destroy 10 Town Halls in Multiplayer battles.
Humiliator II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Destroy 100 Town Halls in Multiplayer battles.
Humiliator III (1,000 in-game XP / 50 Gems / 2,500 Google Play XP)	Destroy 2,000 Town Halls in Multiplayer battles.
League All-Star (100 in-game XP / 250 Gems / 500 Google Play XP)	Join the Crystal League.
League All-Star II (500 in-game XP / 1,000 Gems / 1,500 Google Play XP)	Reach the Master League.
League All-Star III (2,000 in-game XP / 2,000 Gems / 3,000 Google Play XP)	Become a Champion!
Mortar Mauler (10 in-game XP / 5 Gems / 500 Google Play XP)	Destroy 25 Mortars in Multiplayer battles.
Mortar Mauler II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Destroy 500 Mortars in Multiplayer battles.
Mortar Mauler III (1,000 in-game XP / 20 Gems / 2,500 Google Play XP)	Destroy 5,000 Mortars in Multiplayer battles.
Nice and Tidy (10 in-game XP / 5 Gems / 500 Google Play XP)	Remove 5 obstacles (trees, rocks, bushes).
Nice and Tidy II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Remove 50 obstacles (trees, rocks, bushes).
Nice and Tidy III (1,000 in-game XP / 20 Gems / 2,000 Google Play XP)	Remove 500 obstacles (trees, rocks, bushes).
Release the Beasts (10 in-game XP / 5 Gems / 500 Google Play XP)	Unlock Archer in the Barracks.
Release the Beasts II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Unlock Wall Breaker in the Barracks.
Release the Beasts III (1,000 in-game XP / 20 Gems / 2,000 Google Play XP)	Unlock Dragon in the Barracks.
Spoils of War (100 in-game XP / 25 Gems / 500 Google Play XP)	Collest 800,000 Gold in Clan War bonuses.
Spoils of War II (500 in-game XP / 100 Gems / 1,000 Google Play XP)	Collect 15,000,000 Gold in Clan War bonuses.
Spoils of War III (5,000 in-game XP / 1,000 Gems / 2,000 Google Play XP)	Collect 100,000,000 Gold in Clan War bonuses.
Sweet Victory! (10 in-game XP / 5 Gems / 500 Google Play XP)	Achieve a total of 75 trophies in Multiplayer battles.
Sweet Victory! II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Achieve a total of 750 trophies in Multiplayer battles.
Sweet Victory! III (1,000 in-game XP / 450 Gems / 3,000 Google Play XP)	Achieve a total of 1,250 trophies in Multiplayer battles.
Unbreakable (10 in-game XP / 5 Gems / 500 Google Play XP)	Successfully defend against 10 attacks.
Unbreakable II (100 in-game XP / 50 Gems / 1,000 Google Play XP)	Successfully defend against 250 attacks.
Unbreakable III (1,000 in-game XP / 100 Gems / 2,000 Google Play XP)	Successfully defend against 5,000 attacks.
Union Buster (10 in-game XP / 5 Gems / 500 Google Play XP)	Destroy 25 Builder's Huts in Multiplayer battles.
Union Buster II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Destroy 250 Builder's Huts in Multiplayer battles.
Union Buster III (1,000 in-game XP / 30 Gems / 1,500 Google Play XP)	Destroy 2,500 Builder's Huts in Multiplayer battles.
Wall Buster (10 in-game XP / 5 Gems / 500 Google Play XP)	Destroy 10 Walls in Multiplayer battles.
Wall Buster II (100 in-game XP / 10 Gems / 1,000 Google Play XP)	Destroy 100 Walls in Multiplayer battles.
Wall Buster III (1,000 in-game XP / 20 Gems / 2,000 Google Play XP)	Destroy 2,000 Walls in Multiplayer battles.
War Hero (50 in-game XP / 50 Gems / 500 Google Play XP)	Score 10 stars for your clan in Clan War battles.
War Hero II (500 in-game XP / 200 Gems / 1,000 Google Play XP)	Score 150 stars for your clan in Clan War battles.
War Hero III (1,000 in-game XP / 1,000 Gems / 2,500 Google Play XP)	Score 1,000 stars for your clan in Clan War battles.
X-Bow Exterminator (50 in-game XP / 50 Gems / 500 Google Play XP)	Destroy one X-Bow in a Multiplayer battle.
X-Bow Exterminator II (100 in-game XP / 100 Gems / 1,000 Google Play XP)	Destroy 250 X-Bows in Multiplayer battles.
X-Bow Exterminator III (1,000 in-game XP / 200 Gems / 2,000 Google Play XP)	Destroy 2,5000 X-Bows in Multiplayer battles.