I'm running a sci-fi campaign using D&D 5e, Ultramodern 5e (an add-on that allows you to run modern and sci-fi settings using D&D 5e), with Esper Genesis space combat rules. I have a player who's planning to acquire a spacesuit and, when space combat begins, jump out the airlock and start using spells to shoot at spaceships.

My main problem is that the ships are really really big and they've been balanced around ship weapons, not player spells. I worry that if I let his spells affect a ship it'll just instantly vaporize any enemy. I know Starfinder doesn't let player weapons and spells affect ships and I'm wondering if I should implement this. What should I do?

  • 13
    \$\begingroup\$ Note that this question is using modifications to the standard 5e rules, answerers should be experienced with those modules and what changes they make and not just assume that no relevant rules have been added/changed. \$\endgroup\$ Sep 26, 2019 at 14:21
  • 2
    \$\begingroup\$ I've opened this meta to discuss the use of an Ultramodern5e and Esper Genesis tag. \$\endgroup\$
    – goodguy5
    Sep 26, 2019 at 14:37
  • \$\begingroup\$ Is there some specific spell you're worried about? While I'm not familiar with the sci-fi add-ons, I'm trying to imagine what would be any different than in a traditional D&D campaign involving ships on an ocean? Could you give some more concrete examples of your "worry"? \$\endgroup\$
    – user37158
    Sep 26, 2019 at 16:07
  • \$\begingroup\$ @PeterCooperJr. any damage spell like fire ball, fire bolt, and eldritch blast. \$\endgroup\$
    – Gwideon
    Sep 26, 2019 at 16:11

1 Answer 1


The Esper Genesis Basic Rules state:

Starship defenses include fortified frames, polarized plating, and energy shields, all of which make them fairly resistant to attacks from handheld weapons. If it becomes necessary to calculate a ship's durability in creature terms, multiply the hull points by 10, and add resistance to slashing, piercing, and bludgeoning damage.


ships in combat slow down to their intercept speed, which is measured in 50-foot increments known as units.

Most of the sample ships have a speed of 30 units (1500 feet).

This seems to suggest that it's perfectly possible for characters to exit a ship in a spacesuit and make attacks, but the conversion from hit point damage to hull point damage may not be favorable, and the ranges involved in ship combat mean that most enemy ships might be far out of range for spellcasting, most of the time.

I did not see any rules for calculating damage if a character in a spacesuit is hit by a ship weapon, but if one hull point equals ten hit points and many ship weapons deal 1d6 hull damage, that could work out to quite a lot of damage.


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