As an eladrin from Mtof, I have access to the fey step ability. I have already decided to take at least a couple levels of rogue. Assuming I can multi-class my character, is there any way to get the range of that teleport up? If not, is there a way to improve its "once per short rest" status?
Possible improvement with variant Eladrin race
A variant of the Eladrin race was released in Mordenkainen Presents: Monsters of the Multiverse†. Along with some other minor changes, the MPMM Eladrin's version of Fey Step reads (emphasis mine):
As a bonus action, you can magically teleport up to 30 feet to an unoccupied space you can see. You can use this trait a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.
If your DM allows this material, and would allow you the change, it may (or may not) be an improvement to its "once per short rest" status. Whether it is better is heavily dependent on the frequency of short rests in your game, as the MPMM version replenishes only on a long rest. This version does scale up as proficiency bonus increases, so it may be worth more at later levels.
Other means for short teleports
While not exactly the same as the Eladrin teleport, there are other ways to get access to a short teleport for your rogue. To name a couple:
- The Fey Touched feat lets you cast misty step once per day
- The rare magic item Cape of the Mountebank lets you cast dimension door once per day
† Note: As of this writing, Mordenkainen Presents: Monsters of the Multiverse has only been released as part of the Dungeons & Dragons Rules Expansion Gift Set, the book as a standalone is not set to release until May 2022.
Get a familiar
I cannot help you with increasing the range or the frequency, but I can help you none-the-less. I think you are not looking in the right place to massively increase the power of Fey Step.
Fey Step. As a bonus action, you can magically teleport up to 30 feet to an unoccupied space you can see. Once you use this trait, you can't do so again until you finish a short or long rest.
(Emphasis mine). The limitation to see where you are teleporting to is much more severe than wether you have a 30 or 60 foot range. Imagine you could see through walls, doors etc. Then your Fey Step would suddenly grant you access to barred fortresses, locked up treasure vaults, secret rooms -- you get the idea. Well, you can, if you get a familiar with the Find Familiar spell, either from taking one level of wizard, or from taking the Magic Initiate feat. Apart from all the other advantages a familiar brings (such as helping you on your perception checks for advantage, help your attacks in owl form for advantage and Sneak Attack, scouting ahead for you, etc. pp.) it comes with this feature:
As an action, you can temporarily dismiss your familiar. (...) As an action while it is temporarily dismissed, you can cause it to reappear in any unoccupied space within 30 feet of you.
Note it does not say anything about you being able to see the space where it appears. This is not casting a spell either, so you need no line of effect. You can just have it pop back into the world behind that wall or door in front of you. Then:
While your familiar is within 100 feet of you, you can communicate with it telepathically. Additionally, as an action, you can see through your familiar's eyes and hear what it hears until the start of your next turn
You look through your familiars eyes as an action, seeing the area on the other side of the wall or door. Then you Fey Step there as a bonus action.
Effectively you get most of the power of Dimension Door, a level four spell. (Let me add that I, like many others here find this is a very cheesy use of the familiar, and would support a DM ruling it can only re-appear in a space that can be seen. So you might want to check with your DM if he is OK with this strategy, before implementing. This is always advisable to avoid problems.)
Unfortunately, you are stuck with what is written in the trait, unless you take a feat.
There is no way to improve this racial trait. It is not a spell, so features that modify spells won't work.
However, there is a feat that will get you what you want, Fey Touched:
You learn the misty step spell and one 1st-level spell of your choice. The 1st-level spell must be from the divination or enchantment school of magic. You can cast each of these spells without expending a spell slot. Once you cast either of these spells in this way, you can’t cast that spell in this way again until you finish a long rest. You can also cast these spells using spell slots you have of the appropriate level. The spells’ spellcasting ability is the ability increased by this feat.
Misty step has the same effect as your Fey Step feature, and this feat gives you an additional use-per-long-rest, and if you are playing a class that uses spell slots, allows you to use them to cast the spell. Sow hile this doesn't actually improve your trait, at the cost of a feat you can get what you are looking for - more teleportation. Fey Touched does have the advantage of being a "half-feat", meaning that it also allows you to increase one of your ability scores by one.