[RPG] Can beasts benefit from magic items

You are using the table wrong.

The table assumes you have a magic item in mind and are trying to determine the cost. It is a not a table that you should be grabbing lines from to combine to form magic items.

That said, the entries:

• Single use, spell completion
• Single use, use-activated
• 50 charges, spell trigger

do not normally interact with (and if they do, they do not do a good job estimating actual price):

• Charges per day
• Charged (50 charges)

The first set are intended to price out single use or limited use items that eventually cease to exist or become inert like potions, scrolls, and wands.

The second set are there help determine costs for magic items that continue to exist forever until destroyed such as staffs and wondrous items.

Remember, the table is only there to estimate the cost of a magic item. It is not completely accurate and you should usually consult similar magic items for their price.

The text is clear. The horseshoes may only be used by ordinary horses, and any user transforms into a 'creature resembling a Nightmare' (though any such changes, are, of course, superficial). However, a DC 25 UMD check allows a Minotaur (or any other creature, regardless of whether it has hooves or not) to count as an ordinary horse for the purposes of the item via the Emulate a Race option.