The Must Obey spell is a continuous spell which forces your creatures to work more efficiently. For however long the spell lasts, it increases the speed of all of your creatures by 25 percentage points and forces them to perform all of their tasks much more quickly (similarly to being slapped), as well as locks their happiness level. The spell is similar to Call to Arms in that it is a continuously-running spell, and costs 25 gold per second until it is cancelled or the player runs out of money. This spell is very useful if one has a large amount of money or access to gems, but can be quite costly otherwise. If Creatures are angry while the spell is in action, they will not perform their Anger Job. In Dungeon Keeper FX, the spell also allows the player to force creatures to do jobs they hate, as claimed in the manual that came with the game.
| ||Armageddon / Call to Arms / Cave-In / Chicken / Conceal Monster / Create Imp / Destroy Walls / Disease / Heal / Hold Audience / Lightning Strike / Must Obey / Possess Creature / Protect Monster / Sight of Evil / Speed Monster|
| ||Call to Arms / Chicken / Create Gold / Create Imp / Heal / Inferno / Possession / Sight of Evil / Summon Horny / Thunderbolt / Tremor / Turncoat|
| ||Assembly / Create Imp / Deception / Detection / Electric Shock / Enchant / Exorcism / Heal / Possession / Seismology|
| ||Time Bomb|