D&D 5E Combining magical item qualities or potion effects

[Elderbrain]

Suppose I want to create a "new" magical item that has the qualities of two already existing items (i.e. two different potions, two wands, a vorpal sword + a sword of sharpness, etc.) How should I determine the new rarity and value of the combined item? Add the prices of the separate items?

 

[aco175]

I do not remember seeing much in terms of cost for items, except minor potions and such. I would triple the cost of anything you think. I would just double something added to +1 something. Example; +1 sword cost 5,000gp (made this number up). If you wish to add cloak of displacement properties to it, maybe add another 5,000 instead of 10,000. If you wish to add the displacement to something without a basic +1 such as boots of levitation I would add the 10,000.

After re-reading this I may make the numbers higher depending on how much you use attunement. Combining items above gets you basically one more item for free.

 

[dagger]

The prices in the DMG are a major failure of randomness.

Start with this:

http://www.giantitp.com/forums/showthread.php?424243-Sane-Magic-Item-Prices

 

[Cap'n Kobold]

D&D 3.5 multiplied the second item price by 1.5 if you wanted to combine effects into a single item. I'd suggest something along those lines. A single item that does everything that two other items do should cost more than just the two items.
I'd suggest that you increase the modifier if the original items involved require attunement.