Here is the full list of all 221 Army of Ruin achievements.
Forge III - Complete the Stage without opening any chest
Upgrade Anvil of Heaven to Level 5
Forest III - Complete the Stage without taking any damage
Reach Experience Level 30 with Traxx
Shrine ∞ - Reach Minute 30
Reach Experience Level 40 with Azazel
Upgrade Chain Lightning to Level 5
Glacier Stage III - Ruin 3 - Pick 3 Charms with Kroat
Shrine III - Ruin 3 - Evolve 3 weapons with Abaddon
Glacier III - Complete the Stage with no Capacity Upgrades
Graveyard Stage III - Ruin 3 - Defeat all special bosses with Obsidian Crown
Upgrade Pirate Cutlass to Level 5
Forest Stage II - Ruin 3 - Earn 4,000 Coins with Saul
Glacier Stage III - Ruin 2 - Reach Experience Level 35 with Bhask
Glacier Stage III - Earn 4,000 Coins with Homemade Explosives
Glacier Stage III - Ruin 1 - Complete the Stage with Frozen Shard
Forge Stage I - Ruin 3 - Complete the Stage with Pirate Anchor
Glacier Stage ∞ - Reach Minute 30
Upgrade Hitman Goggles to Level 5
Shrine II - Complete the Stage without opening any chest
Reach Experience Level 40 with Midas
Upgrade Living Paintbrush to Level 5
Glacier Stage II - Ruin 3 - Earn 5,000 Coins with Neptune
Glacier II - Complete the Stage without moving
Graveyard III - Complete the Stage spending 20,000 or less in Upgrades
Forest II - Complete the Stage spending 5,000 or less in Upgrades
Forge I - Complete the Stage without purchasing any Upgrade
Graveyard II - Complete the Stage without taking any damage
Forge Stage III - Ruin 3 - Complete the Stage with Toxic Stench
Forge Stage ∞ - Reach Minute 30
Reach Experience Level 40 with Neptune
Upgrade Ink Geyser to Level 5
Reach Experience Level 30 with Diana
Upgrade Bronze Starfish to Level 5
Graveyard Stage ∞ - Reach Minute 30
Upgrade Chain Shot to Level 5
Unlock 200 items (Characters, Equipment and Features)
Upgrade Unfulfilled Promises to Level 5
Reach Experience Level 30 with Michi
Upgrade Throwing Bombs to Level 5
Shrine III - Ruin 1 - Complete the Stage with Magic Needle
Graveyard Stage II - Ruin 3 - Kill 7500 enemies
Reach Experience Level 30 with Nekros
Upgrade Dark Staff to Level 5
Forest Stage III - Ruin 3 - Reach Experience Level 40 with Tisha
Glacier Stage I - Ruin 3 - Evolve 3 weapons with Kyros
Graveyard Stage III - Ruin 2 - Defeat all special bosses with Experiment XIX
Glacier Stage II - Ruin 2 - Complete the Stage with Tisha and Explosive Flask,Seal of Purity
Forge Stage III - Ruin 2 - Complete the Stage with Mork, and infuse Fire Fire Fire
Upgrade Divine Top to Level 5
Shrine III - Complete the Stage infusing Wind Wind Wind
Upgrade Fiendish Tear to Level 5
Shrine III - Complete the Stage without infusing any Earth
Upgrade Command Baton to Level 5
Upgrade Wanderer's Lantern to Level 5
Shrine III - Complete the Stage
Shrine III - Complete the Stage with 28:00 minutes or more on the clock
Upgrade Promethean Flames to Level 5
Reach Experience Level 40 with Experiment XIX
Upgrade Sparksword to Level 5
Forge Stage III - Ruin 1 - Complete the Stage with Ancestral Razor
Graveyard Stage III - Ruin 1 - Complete the Stage with Ker
Upgrade Jade Wand to Level 5
Upgrade Landslide to Level 5
Forest Stage ∞ - Reach Minute 30
Upgrade Swift Tornado to Level 5
Reach Experience Level 25 with Kroat
Upgrade Ominous Gale to Level 5
Forge Stage III - Upgrade Golden Trident to Level 5
Glacier Stage I - Ruin 1 - Complete the Stage with Obsidian Crown
Glacier Stage III - Complete the Stage without infusing any Earth
Glacier Stage III - Complete the Stage
Reach Experience Level 40 with Abaddon
Upgrade Sphere of Destruction to Level 5
Upgrade Magatama to Level 5
Forest Stage III - Ruin 2 - Defeat all special bosses with Bhask
Upgrade Ancestral Razor to Level 5
Shrine II - Complete the Stage infusing Ice Ice Ice
Shrine II - Complete the Stage with Rotting Coil,Poison Root,Elven Bow
Forge Stage III - Upgrade Leather Bracer to Level 5
Forge Stage III - Complete the Stage
Reach Experience Level 25 with Tabia
Upgrade Marksman's Crossbow to Level 5
Shrine II - Ruin 2 - Defeat all special bosses with Samael
Shrine II - Ruin 1 - Complete the Stage with Onyx Coin
Forge Stage II - Ruin 3 - Upgrade Panacea to Level 5
Forest Stage III - Ruin 1 - Defeat all special bosses with Lanyz
Forge Stage II - Ruin 2 - Complete the Stage with Jellyfish Ashes
Upgrade Jellyfish Ashes to Level 5
Unlock 150 items (Characters, Equipment and Features)
Forest Stage III - Upgrade Ranger Bow to Level 5
Forest Stage III - Complete the Stage with Meteorite Blast
Upgrade Caltrops to Level 5
Upgrade Mighty Punch to Level 5
Forge II - Complete the Stage with 22:00 minutes or more on the clock
Upgrade Brittle Stone to Level 5
Shrine I - Complete the Stage without moving
Glacier I - Complete the Stage without taking any damage
Upgrade Magical Slingshot to Level 5
Reach Experience Level 25 with Mork
Graveyard I - Complete the Stage without moving
Forest Stage III - Complete the Stage
Reach Experience Level 40 with Samael
Forest Stage II - Ruin 2 - Complete the Stage with Buckler
Upgrade Lapis Sword to Level 5
Forge Stage II - Ruin 1 - Defeat all special bosses with Ogol
Shrine I - Ruin 1 - Complete the Stage with Devilish Eye
Forge Stage I - Ruin 2 - Complete the Stage with Ice Mirror
Upgrade Pirate Anchor to Level 5
Upgrade Ghostly Trail to Level 5
Forest Stage I - Ruin 3 - Complete the Stage with Voodoo Doll
Upgrade Battle Cog to Level 5
Upgrade Fire Wings to Level 5
Forest I - Complete the Stage with 16:00 minutes or more on the clock
Reach Experience Level 25 with Tisha
Upgrade Cupid's Arrow to Level 5
Shrine II - Complete the Stage
Forest Stage II - Ruin 1 - Complete the Stage with Bhask
Glacier Stage I - Ruin 2 - Complete the Stage with Selina, without infusing any Darkness
Upgrade Frozen Shard to Level 5
Upgrade Silvan Shell to Level 5
Glacier Stage II - Ruin 1 - Complete the Stage with Supply Crate
Pick 3 Charms
Graveyard Stage III - Complete the Stage with Storm Javelin
Graveyard Stage III - Reach Experience Level 30 with Ker
Earn 30 Stars
Graveyard Stage II - Ruin 2 - Defeat all special bosses with Ker
Reach Experience Level 15 with Ker
Upgrade Ranger Bow to Level 5
Graveyard Stage I - Ruin 3 - Reach Experience Level 30 with Lanyz
Glacier Stage II - Evolve Necromancer Gauntlets
Graveyard Stage III - Complete the Stage
Glacier Stage II - Complete the Stage with War Drums
Glacier Stage II - Complete the Stage
Upgrade Necromancer Gauntlets to Level 5
Forge Stage I - Ruin 1 - Complete the Stage with Lanyz
Forge Stage II - Reach Experience Level 30 with Ogol
Forge Stage II - Reach Experience Level 30 with Saul
Upgrade Homemade Explosives to Level 5
Unlock 100 items (Characters, Equipment and Features)
Graveyard Stage II - Ruin 1 - Defeat all special bosses with Ariana
Graveyard Stage I - Ruin 2 - Complete the Stage with Whirlwind Pickaxe
Upgrade Mystical Firecrackers to Level 5
Upgrade Fire Staff to Level 5
Pick 1 Charms
Evolve 4 weapons
Forge Stage II - Complete the Stage
Earn 21 Stars
Upgrade Blaze to Level 5
Shrine I - Upgrade Wolf's Fang to Level 5
Earn 20 Stars
Shrine I - Upgrade Ice Tear to Level 5
Reach Experience Level 15 with Bhask
Forest Stage II - Upgrade Armor of Thorns to Level 5
Unlock 60 pieces of equipment (Weapons and Trinkets)
Earn 18 Stars
Forest Stage II - Complete the Stage with Energy Bolt
Upgrade Golden Trident to Level 5
Upgrade Whirlwind Pickaxe to Level 5
Forest Stage II - Complete the Stage
Reach Experience Level 25 with Kyros
Earn 17 Stars
Earn 16 Stars
Upgrade Flintlock Pistols to Level 5
Shrine I - Complete the Stage
Defeat 100 bosses through all stages
Upgrade Throwing Axe to Level 5
Graveyard Stage I - Ruin 1 - Complete the Stage with Viking Helm
Upgrade Energy Bolt to Level 5
Upgrade Meteorite Blast to Level 5
Forest Stage I - Ruin 1 - Defeat all special bosses with Saul
Earn 15 Stars
Graveyard Stage II - Upgrade Travel Boots to Level 5
Die a total of 10 times
Use your skill 200 times through all stages
Upgrade Quicksilver Spears to Level 5
Glacier Stage I - Reach Experience Level 25 with Ogol
Earn 30,000 Coins through all stages
Use the Bomb Power 10 times through all stages
Use the Freeze Power 10 times through all stages
Forge Stage I - Upgrade Magnifier to Level 5
Upgrade Wolf's Fang to Level 5
Die a total of 5 times
Earn 12 Stars
Graveyard Stage II - Complete the Stage with Magic Staff
Use the Haste Power 10 times through all stages
Upgrade Spectral Dagger to Level 5
Unlock 50 items (Characters, Equipment and Features)
Win a total of 6 stages
Graveyard Stage II - Complete the Stage
Earn 20,000 Coins through all stages
Earn 10 Stars
Glacier Stage I - Upgrade Toxic Stench to Level 5
Reach Experience Level 15 with Lanyz
Upgrade Toxic Stench to Level 5
Glacier Stage I - Complete the Stage
Forge Stage I - Earn 750 Coins
Earn 8 Stars
Forge Stage I - Complete the Stage
Forest Stage I - Upgrade Volcanic Orbs to Level 5
Upgrade Volcanic Orbs to Level 5
Earn 5 Stars
Use your skill 15 times
Upgrade Storm Javelin to Level 5
Upgrade Magic Staff to Level 5
Upgrade Crawling Root to Level 5
Forest Stage I - Complete the Stage
Forest Stage I - Complete the Stage with Throwing Axe
Kill 3000 enemies
Reach Experience Level 15 with Ogol
Graveyard Stage I - Reach Experience Level 20 with Ariana
Earn 500 Coins
Open 5 Chests
Upgrade Dragon Heart to Level 5
Reach Experience Level 15 with Ariana
Graveyard Stage I - Upgrade Crawling Root to Level 4
Earn 5,000 Coins through all stages
Earn 2 Stars
Reach Experience Level 25
Graveyard Stage I - Complete the Stage
Reach Experience Level 15 with Saul