Here is the full list of all 24 God Mode achievements.
Trigger 20 Mage seals
Fully upgrade one weapon
Survive the "Death" Test of Faith
Finish any map with 3 or more active Oaths
Decapitate 100 Skeletons
Complete any map without dying
Complete your first Oath
Purchase your first weapon upgrade
Finish any map on any difficulty
Kill 100 creatures
Kill 2500 creatures
Destroy 50 scarab eggs before they hatch
Enrage 10 Cyclops
Kill 50 enemies using melee
Grind 50 creatures using the Buzzsaw melee attack
Reach the final level and attain God Mode
Purchase all upgrades
Finish any map with 6 active Oaths on hardest difficulty
Kill 20 creatures using the Hammer ability
Complete all maps on hardest difficulty
Kill 25 000 creatures
Buy Super Pants
Collect 5 000 000 unspent gold
Complete any map on Platinum difficulty