
They activate when certain conditions are met.
Hell's Seal: The Devil gains the ability to place Hell's Seals on allies. If a saving throw is involved, its DC is 10+ double the devil's mythic rank. Hell's Decree: As you become a Devil, you gain the ability to issue Hell's Decrees a number of times per day equal to his mythic rank. Should you reject him in the Abyss but accept on the Azatan island, he will simply trick you into killing your allies and then try to kill you anyway, resulting in losing a Mythic level. Note that, for those initially following the Azata path, you must agree to Early Sunset's offer during the Aivu quest in the Abyss to be eligible for the Devil mythic path. He will offer you the Devil route if you choose to kill all the inhabitants of the Azatan island. After you return to the Abyss, continue the questline involving the Azatan island. During the abyss, once Aivu is kidnapped, do the sidequest to rescue Aivu. Take him as an advisor and follow his court suggestions. For Azata, an Azatan named Early Sunset will arrive in your court.
There will be a trial to determine your eligibility for the Devil route. You will need to pass several Diplomacy checks to succeed in his trial.
Later after you returned from abyss, he will show up again and offer you the chance to become a devil. Take him as an advisor, and be cooperative.
For Aeon, a devil named Melies shall appear in your court.
Unlock: Must chose Azata or Aeon path first after you take Drezen. Masters of corruption and despoilers of purity, devils seek to destroy all things good and drag mortal souls back with them to the depths of Hell."
"Devils are lawful evil outsiders that hail from the plane of Hell. You can bind others through seals and contracts, and use your power to dominate the forces of chaos. A cunning and evil manipulator, you enforce your will upon those around you. Devil is a Mythic Path in Pathfinder: Wrath of the Righteous.