A lot of the superstitions we have today are leftovers from earlier times. The meanings of many of them have changed over the years. Some of them are ritualistic behavior meant to bring good luck or protect against supernatural influences. Others are things to avoid for fear of acquiring bad luck.
What would superstitions be like in a world where magic is demonstrably real?
Some settings tackle this issue dead-on. In Exalted, for instance, anyone who has a rating in the Occult skill can perform simple rituals. These aren’t necessarily particularly powerful – they might help to preserve food for an extra day or enact a very short-lived ward that will make it a bit harder for, say, the powers of ghosts to have an effect on you. Also, Exalted’s world is an animistic one. Everything has a spirit. The spirit of your iron pot might not be conscious – but if you interact with it in certain ways if might gain a bit of power that would help it in its tasks. On the other hand, the spirit of the river is conscious – and the poetry that you read to the river really does placate it so that it regulates its flooding in convenient ways. In this setting, this is real magic and spirit interactions. Superstitions still exist in such a world – many of them are corrupted forms of rituals and spirit interactions. People might throw apples into the river, thinking that it will please the river-spirit who will then protect them from drowning, but it might be that the river spirit doesn’t particularly care about apples one way or another (or the bargain it made regarding apples was with a particular individual 300 years ago and no longer applies). Alternately, people might have jumbled the food-preservation ritual in a particular area and may not realize that it has no effect.
I think that, to some degree, this can be generalized to other settings. It doesn’t make a whole lot of sense for superstitions in a fantasy world to be wholly divorced from magic in that world. So, for instance, in a D&D campaign we might see superstitions like:
- A gesture that wards against the evil eye might be remarkably similar to a somatic component to the Shield spell… or a word said for good luck might be a corruption of some of the verbal components of a Heroism or Remove Curse spell
- A ward against evil entering your house might include a god’s holy symbol – seen used as a divine focus for turning undead
- Rose petals adorning a baby’s crib might be seen as helping it to sleep (rose petals as a material component of the sleep spell)
- Suitors may eat honeycomb (a component of the suggestion spell) before attempting to, umm, press their case
In addition, ingredients to potions and such could be used. Metamagic components are a great place to look for inspiration if your campaign uses such rules.
In 4e, the components to rituals are generally left vague – but that doesn’t mean that they don’t have concrete components. An arcana (or religion, as appropriate) check might be used to identify the roots of superstitions.