Command Word NO

When the specified target within range declares an action on their turn, you can cast this word of command as your reaction to force them to choose to do something different. The target can pick any other action available to it, but it cannot be the same as the action type it was going to take. For example if the spell was used against a creature who was going to make a melee attack against a specific target, it now cannot use their action to make a melee attack, they could instead, if available make a ranged attack, or cast a spell, or disengage or any other action except for the one they were about to do when the spell was cast. 

The spell has no effect if the target is undead,  or if it is immune to charm effects.