The Devil and Hell are Judeo/Christian constructs that are NOT shared by non-christian Yoruba and are not a part of traditional Yoruba theology nor as I recall Lucumi. Interestingly, christian missionaries saw esu (eshu/elegba) and because of his potential to be wrathful and known to do "evil" things, they equated him with the devil. When they wrote Yoruba/English dictionaries, they actually went so far as to put Esu as the Yoruba word for the devil, and many Christian Nigerians believe he is the devil and sadly use his name for the Devil in Yoruba. We of course know that Esu is not the devil, though he can be devilish! :-)
That is not to say the Yoruba don't have beings/forces of nature that can perform acts that fall outside of the moral constructs of what we might call "good", and there are certain people who try and utilize the Iyaami for what might be evil purposes. I know also that Aroni, is an imp like creature that is known to
reek havoc in what might be considered an evil way. Perhaps they imbody the ability and nature of chaos, which can run counter to our own needs/desires/wants, which then are interpreted as "evil".
There is not, however, the same dialectic thesis/antithesis as christianity. There is no devil that is trying to win our souls or beat God (Olodumare), but there are "evil things that go bump in the night".
Esu, Aje, Ajoogun, Iyaami. They are to be spoken of in hushed voices (prayers to the iyaami are never spoken loudly,only in a voice above a low tone and are revered and never upset. There are many odu that
talk about the Iyaami for instance, even thwarting the works of Orunmila and other Orisha unless they are appeased. The Yoruba believe we make our own choices and we can certainly make evil ones
ourselves, and they can be affected by evil things, but evil is simply a part of nature, not someone who is the antithesis of god and always trying to "win" the world away from some holy salvation.
There is no hell at all that I've ever heard of . . . which is probably where reincarnation comes in, those people who are wicked do not become one of the Isheshe and reincarnate choosing their destiny each time they do. I suppose now that I think of it, it's much more akin to the buddhist concept. Our Ori is kunle (kneeling) in front of Olodumare as it picks it's destiny, to which Ifa/Orunmila is witness (Eleri Ipin). Obatala then creates the body, Ajala the head and the Emi is given by Olodumare. Because of a time when Ebo was not correctly offered to Elenini, we forget our destiny as we pass through the birth canal. Ori however, has left it's Enikeji (heavenly/spiritual double) in orun to remind us of our chosen destiny and it is our job to always try and recall our chosen path. If we have good character, we can fulfill our destiny and lead a good life.
More thoughts on Yoruba theology.