This enchantment allows the player to step up blocks so they don't have to jump and use up their exhaustion bar. There are 3 levels for this enchantment which provide greater and greater amounts of step assist. This enchantment is restricted to the boots slot of armor.

The ranks described below include the maximum height of step assist provided regardless of other mods. For example, if a mod provides a way to get 1 block of step assist then Rank 1 of the enchantment will not give you 2 blocks of step assist since the maximum provided by that rank of enchantment is 1 block. It is specifically designed to not stack.

Also if the player is using the built-in "Auto-Jump" feature provided by Minecraft, the enchantments will not work since you are using a different feature which kind of does the same thing.

If you turn the Step Assist off (or the server admin does), the enchantments will still be on your boots (so you don't lose them if they were previously applied) however they will have no affect on your step height.

There are 3 ranks of step assist.

1. "Step Assist I" gives you 1 block of step height. This is the same step height which horses get so you can automatically climb 1 block high blocks.
2. "Step Assist II" gives you 1.5 blocks of step height. This allows you step up to fences/walls since they are considered 1.5 blocks high.
3. "Step Assist III" gives you 2 blocks of step height. This allows you to climb hills and mountains easier as they typically have areas were there are 2 blocks difference between where you are and the next ledge you want to get too.

There is an enchantment book available for those in creative mode or for server admins that want to give it to players (there is no hard-coded enchantment ID though). The first level of Step Assist can be obtained by through the anvil by using any pair of vanilla Minecraft boots and a piece of Fluffy Fabric. This is an item provided by this mod. Using Fluffy Fabric and mod created boots may also work but is not guaranteed.

Below are screen shots of how much the enchantment costs using the Fluffy Fabric.