Runewords are among the most powerful items you can build within Diablo 2: Resurrected, even though they require quite the effort to make. You first need to locate the right runes to make the runeword, then you'll need the weapon or armor, or D2R Items shield that will accept the runeword. The item has to have the precise number of open sockets for the runeword to function, and the runes must be placed into the item that is socketed in the correct order. Also, the item has to be unadorned (white) and magical (blue) and rare (yellow) and unique (gold) as well as set (green) items that have the proper amount of sockets won't work on runewords.
In this regard, you must take extreme care when writing a runeword. Double-check and triple-check that the items's proper type -for instance, the Insight runeword is able to be made using staves and polearms but not spears. Lastly, put the runes out in the proper order before fitting them into the item.
There are some nuances when it comes to weapons and armor to keep track of. "Body armor" can only be defined as items placed on your body. General "armor" includes shields, boots, gloves, helms, etc. Hammers cannot be used using runewords that are intended for maces. "Melee weapons" are not melee weapons, such as bows and crossbows. Orbs also aren't melee weapons.
When creating runewords, many are based on different stats, which determine how good of a roll you've made. A perfect roll of runewords is always worth a lot more than an imperfect roll. Also selecting the most effective runeword base (an item that has sockets) possible is always advised. For instance, if creating a runeword to buy D2R ladder items equip on a mercenary, always choose an Ethereal base. Mercenary weaponry and armor doesn't have a decrease in durability, which means you can get the benefit of stats gained from the Ethereal property and not worry about it ever breaking. Every little boost to stats counts in Diablo 2: Resurrected.