Spelljamming Clarified: Spelljammer 5e Conversion

I want to thank everyone for the comments on the last post. It’s always nice to know that I’m not just shouting into the void. One of the comments was a question about the use of highest available spell slot for determining Spelljamming Rating in the last post. It made me realize that I didn’t do a very good job of explaining why I made this decision. That’s kind of the point of these posts, right?

The original Spelljammer rules called for magic-users without their full complement of spells available to suffer a penalty of one SR per spell cast. I really don’t agree with this rule at all. It is kind of absurd to think that a 20th-level wizard who cast a 1st-level spell, but still had access to more than 30 additional spells suddenly couldn’t operate a spelljammer helm at maximum efficiency. And it gets exponentially more ridiculous as they cast more spells.

This idea works even less in 5e where many of the lower level 2e spells have been converted over to cantrips. Should casting cantrips come along with a penalty for operating a ship? Tracking that just seems like unnecessary extra work for the players and the DM. So my thinking going into this conversion was to lessen the penalty and shape the rule so that it made more sense within the magic system of 5e.

As I’m sure you know the current edition of Dungeons & Dragons uses spell slots. A spellcaster can sometimes choose to cast a low level spell using a higher spell slot. The use of the higher spell slot increases the effectiveness of the spell in some way be, i.e. higher damage, greater range, etc. The way I view this process is that the caster channels a greater amount of their available magical energy into the spell to make a bigger boom. I applied this same idea to the operation of a spelljammer helm. A caster with a 9th-level spell slot available can channel more energy into the helm than one with an 8th-level slot regardless of how many 1st or 2nd-level slots they have used. They are basically casting Spelljam* using a 9th-level spell slot.

An additional concern came over the magic use penalty that comes after operation of a spelljammer helm. The 24 hour restriction comes directly from the original Spelljammer rules, but I think it still makes sense in 5e with one exception. When a caster sits down on a helm or puts on a Crown of Stars they are doing more than just piloting the ship. They are becoming one with the ship itself. This is why a 24 hour restriction makes more sense to me than just a long rest. The process of bonding with a helm should be a more grueling and exhausting process than just simply casting all of your spells. However, 5e magic rules allow for the exception of casting cantrips after using a helm. These spells are not memorized or prayed for. They are just always there so there is no legitimate reason I can think of for them to not be there after using a helm.

I hope that clears my thought process up some for the conversion to this point. I originally planned to go over ship types and armaments in the next post, but I am going to delve a little deeper into ship movement. Not only did I make a math error in the last post that I have corrected, but I realized that post really only skims the surface of ship movement.


4 thoughts on “Spelljamming Clarified: Spelljammer 5e Conversion”

  1. Hi, i realise that I’m a bit late to the party. i’ve been thinking on this myself and will offer my suggestion.

    Using a Spelljamming Helm for just cruising does not prevent you from spellcasting afterwards. This is either a pointless restriction (Okay, having arrived, we’ll rest for 24 hours to let the helmsman get their spells back) or an arbitrary punishment (Hey, how come we go straight into a fight when I was at the helm? Now I can’t do anything!)

    However, during tactical movement, you sacrifice a spell slot to give your ship an SR bonus for that turn. If you use up all your slots, you can trundle along on emergency power (ie, cantrip casting abilities). That means that your spell slots are always used for something worthwhile, and presents meaningful choices: Should I use my last 3rd level spell slot right now to fly the ship in at top speed, or do I need to keep it for the upcoming combat?

    1. Thank you for the suggestions. I agree that the 24 hour restriction for spellcasting was too harsh which is why I have since amended it to a long rest. However, having no penalty at all even for just cruising doesn’t feel right to me for my campaign. I fully reserve the right to change my mind though in a few weeks once our group has gone through an actual session. Are you planning to run a Spelljammer campaign? I would love to get feedback on how it works with the rules as you suggested.

      1. I’ll be running a campaign when the uni society restarts in September. One of the options is a Spelljammer – Eclipse Phase crossover using 5e. I’m starting prep on it nowish.

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