Here is the full list of all 45 Guardians of Holme achievements.
Defeat Baal
Level up Nicole to Lv.5
Win a Boss level after calling in all waves early
Defeat Leviathan
Burn 15 or more units at the same time
Decrease Armor of any monster to below -30
Unlock character Nicole
Level up Seth to Lv.5
Have more than 1000 Gold
Win with more than 30 Trap(s) on the field
Defeat Dumah
Defeat more than 15 enemies in one second
Deal more than 400 damage with a single attack
Purchase and play the game
Watch the credits
Level up Seth to Lv.10
Level up Seth to Lv.20
Level up Nicole to Lv.10
Level up Nicole to Lv.20
Unlock all monsters in the Codex
Complete difficulty Normal
Complete Daily Challenge once
Defeat Mastema
Defeat Mammon
Defeat Beelzebub
Defeat Lucifer
Defeat Azazel
Defeat Abaddon
Have more than 8 card(s) in your hand
Have more than 50 card(s) in your deck
Have less than 5 card(s) in your deck
Win with 1HP
Win without placing more than 5 Trap(s)
Defeat 5 or more Balloon Orcs in one second
Bury 7 or more units in one second
Silence 10 or more units at the same time
Freeze 10 or more units at the same time
Paralyze 10 or more units at the same time
Slow 15 or more units at the same time
Charm 10 or more units at the same time
Have more than 10 allied units on the field
Have more than 30 Frogs on the field
Win a Boss level without taking damage
Have more than 3000 resources during the preparation phase
Pick up all Gold on the map