Iron Dragon Slayer Magic is a form of Dragon Slayer Magic which grants the user characteristics unique to Iron Dragons, allowing them to incorporate the element of iron (and, by extension, of steel) into their body, granting them the ability to change parts of their body (or the entirety of it) into iron, which can be shaped in a number of forms for different purposes, and to produce iron objects.
The Magic relies around the use of iron for both offense and defense, with the user being capable of creating a wide array of weapons from their body to attack the opponents both in melee and from a distance, and to cover their body with iron in order to drastically increase their defensive power, whilst simultaneously heavily boosting their offensive power. Gajeel Redfox also stated that the metal produced by this Magic is stronger than normal iron, something later confirmed by Panther Lily, and is capable of rendering some physical assaults useless.
Being a form of Dragon Slayer Magic, this also allows the user to consume external sources of iron to replenish their strength and restore their body to a healthy state. Although, in a similar manner to Fire Dragon Slayers being unable to ingest their own flames, the user is unable to ingest iron that they themselves create.
If an Iron Dragon Slayer is somehow capable of successfully eating shadows, they will enter Iron Shadow Dragon Mode. In this form, the shadow and iron will fuse, and the user's attacks will possess the properties and destructive ability of both elements as well as the ability to transform their body into shadows, granting them a high level of adaptability. Additionally, an Iron Dragon Slayer may turn their iron into steel if they somehow become able to absorb trace amounts of carbon; said process is still toxic and harmful to their body as it would be to others, but the addition of the natural element changes the composition of their spells, allowing the user to deal enhanced damage and/or break through defenses that their iron could not.