The wish spell enables you to emulate any spell of 8th level or lower.
A Ring of Spell Storing enables you to store up to a 5th level spell inside it for later use.
My question is: can you store a wished spell (of 5th level or lower) into a Ring of Spell Storing?
The Ring of Spell Storing says:
Any creature can cast a spell of 1 through 5th level into the ring by touching the ring as the spell is cast.
However, wish does not cast spells. It duplicates their effects. Wish states that you can use it to:
...duplicate the effect of any other spell of 8th level or lower. You don't need to meet the requirements of that spell, it simply takes effect.
No matter what effect you duplicate, the spell you are casting is still wish. And, because wish is a 9th level spell, it cannot be stored in the Ring.
The spell you cast is wish, the effect is that of a lower level spell.
You could cast wish, and wish to store a spell into the ring of storing, but that isn't just duplicating the effect of the spell, so there may be consequences:
You might be able to achieve something beyond the scope of the above examples. State your wish to the GM as precisely as possible. The GM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong. This spell might simply fail, the effect you desire might only be partly achieved, or you might suffer some unforeseen consequence as a result of how you worded the wish.
The stress of casting this spell to produce any effect other than duplicating another spell weakens you. After enduring that stress, each time you cast a spell until you finish a long rest, you take 1d10 necrotic damage per level of that spell.
What your asking for isn't too big, consider you spent a 9th level slot for a <=5 level spell to go into an item made to hold spells of levels <= 5. So, the DM should be alright to try.
