During the early days of 3.5e I ran the Shackled City Adventure Path. One of my players become the new master of Occipitus and eventually managed to rent Occipitus from the Abyss into the Elemental Chaos with the view of eventually moving it back to the Astral Sea. The same player is now playing his own characters grandson who has been sent to The World to investigate the sudden disappearance of all the demon lords by his demigod grandfather as part of my Out of the Abyss campaign. This new character bears the mark of the smoking eye and so here is the template updated for 5e.
The visible mark of one destined to rule Occipitus, the Sign of the Smoking Eye template imbues a creature with the essence of the Abyssal layer (an evil place tinged with good). Receiving the Sign of the Smoking Eye is a necessary first step on the path to ruling the layer as a demon lord. But because Occipitus isn’t wholly evil, the Sign of the Smoking Eye can also be a useful tool for a creature determined to expunge every trace of evil from the plane and restore it to its Celestial glory.
The Sign of the Smoking Eye enables its bearer to establish morphic control over Occipitus. The previous bearer of the Sign, the fallen angel Adimarchus, could remake the landscape with a wave of his hand, control magic use across the layer, and draw nigh-limitless evil power from the fabric of the plane itself. Such abilities require both immense personal power and mastery of the esoteric techniques of morphic planar control – neither of which is granted with this template. With time, study, and the acquisition of further power, someone with the Smoking Eye template could turn Occipitus into a world that reflects its master’s every desire.
Appearance: The base creature’s left eye is replaced with a magical flame that gives off no heat and does not burn the surrounding flesh. When the eye is open, it provides illumination as a candle. The base creature’s vision is unaffected – he or she can still see through the transformed eye normally. The eye also gives off wisps of bitter smoke. The smoke doesn’t obscure vision, but it does give advantage to creatures trying to track the base creature by scent.
Attacks: The base creature gains a +1 attack bonus on all attacks as the power of Occipitus subtly guides your blows.
Imbued with evil: Regardless of the base creature’s actual alignment, spells and spell-like abilities with that specifically affect good or evil creatures treat you as evil or good as appropriate. Magic items are similarly fooled.
Lie in State: When the base creature dies, his or her body disappears after a number of rounds equal to the base creature’s Hit Dice. The body reappears dead but intact in the Skull’s eye socket on Occipitus. Any equipment the base creature was carrying, holding or wearing at the moment of death is likewise transported to Occipitus – and likewise reconstituted if it was destroyed at the moment of death. Each time this ability used, there is a 20% chance that the base creature loses the Sign of the Smoking Eye template. Dimensional anchor, dimensional lock, and similar spells delay the body’s transportation in this manner, but once the spell effect ends the body transport to Occipitus immediately.
Morphic Potential: A creature with the smoking eye template has the potential to change the landscape of Occipitus through conscious effort, provided the base creature is powerful enough to do so. Details of how this ability can be used are up to the DM, but in any case, no creature of 20th level or lower can wield such power consciously. Over time, even a lower character exerts a subconscious influence on Occipitus, however, and the landscape and the essential nature of the plane changes to conform to the base creature’s alignment and desires.
Saves: The base creature gains +1 bonus on all saving throws – it’s almost as if the layer of Occipitus is looking out for you.