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