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