Big Daddy and Little Sister – Technological Deep Sea Marvels for D&D 5th Edition


The multiverse holds many constants and variables, countless realities, countless possibilities.  Among them are societies aspiring for greatness.  These societies seek to build a utopia far away from the world they find so corrupt.  One such place was the City of Rapture; no gods, no kings, only man.  It was here one could hope to achieve greatness, without everyone else tearing you down with virtues of forced altruism, manipulative institutions and suppression of personal achievement.  It was here one had the power to join the captains of industry, but many forgot that someone had to scrub the toilets.  The bloody king of Rapture himself turned on his own ideals as a con man took advantage of the plight to mobilize an army.  As the final nail in the ideals of rapture, mutated and brainwashed humans bonded to cybernetic diving suits were used as both support for Rapture and part of its crumbling defense.  These sad beasts were dubbed “Big Daddies”, tasked with protecting the equally mutated “Little Sisters” to ensure they harvested the dread drug that overtook the entire city.

And what of the creepy little girls that follow them around?  These poor little children were snatched up by some crooked Dr. Frankenstein and turned into little monsters.  Now, they babble incessant nonsense while draining bodies of the wonder drug that ruined the city.  The macabre display unnerved people before civilization fell apart, but it continues regardless of the squabbling splicers that roam the endless dilapidated halls.

Some realities have taken notice of these metal titans!  From secretive collaborators in the floating City of Columbia (Burial at Sea is canon, deal with it), to various other realms not even likened to the underwater city; horrible new creations have arisen after being inspired by Big Daddies  and the Little Sisters themselves.

Author’s Note:  BioShock remains to be one of my favorite games.  So I figure to keep in line with my horror-theme for October, I’d convert one of the most iconic parts of the franchise; Big Daddies and Little Sisters.


Big Daddy

Large humanoid (augmented), lawful neutral

Armor Class 18 (diving armor)

Hit Points 165 (22d10+44)

Speed 25 ft.

STR 18 (+4) DEX 18 (+4) CON 15 (+2) INT 11 (+0) WIS 15 (+2) CHA 15 (+2)

Damage Immunities. poison; bludgeoning, piercing, slashing from non-magical weapons

Condition Immunities. frightened, poisoned, sleep

Senses darkvision 60 ft., Passive perception 10

Languages understands Common

Challenge 10 (5,900 XP)

Charging Smash.  When the Big Daddy makes a dash action, it may use a bonus action to still attack you with disadvantage.

Equipped for the Job.  While Big Daddies look like they were made for maintaining the City of Rapture, they were forged to protect the Little Sisters, who harvest the ADAM drug that turned the city mad.  Big Daddies have a choice of a drill or a rivet gun, as well as related attacks.  As such, they are referred to as Bouncers and Rosies, effectively.

Proximity Mine.  Rosy Big Daddies can set up Proximity Grenades as traps.  When the mine makes contact with an enemy target (including if they’re hit by an attack by one), they must make a Dexterity saving throw (DC 16) or take 30 (4d12+4) force damage.  Successful save halves the damage.

Diving Suit.  The Big Daddy’s advanced diving suit is cybernetically bonded to them.  As such, it enhances their physical abilities, allows for them to take immense punishment, allows them to breath underwater, and efficiently protect their little sister companions.


Multiattack.  Bouncers may use a combination of drill and body slam.  Rosies may make two rivet gun attacks or a rivet gun and a proximity grenade toss attack.

Drill (Bouncer Version Only). Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 43 (5d10+4) piercing damage.

Body Slam (Bouncer Version Only).  Melee Weapon Attack: +8 to hit, reach 5 ft., one target.  Hit: 22 (4d8+4) bludgeoning damage.  Target must succeed a DC 16 Dexterity saving throw or be pushed 15 ft. back.

Rivet Gun (Rosy Version Only).  Ranged Weapon Attack: +8 to hit, range 30/120 ft., one target.  Hit: 26 (4d10+4) piercing damage.

Proximity Grenade Toss.  Ranged Weapon Attack: +8 to hit, range 15/80 ft., one target.  Hit: 11 (2d6+4) bludgeoning damage.  Alternatively, the Rosy can set up the grenade as a trap, missing the target.


Little Sister

small humanoid (augmented), chaotic neutral

Armor Class 13

Hit Points 13 (2d6+4)

Speed 30 ft.

STR 10 (+0) DEX 16 (+3) CON 15 (+2) INT 11 (+0) WIS 16 (+3) CHA 14 (+2)

Condition Immunities. frightened, charmed, sleep

Skills.  Perception +6, Stealth +6

Senses darkvision 60 ft., Passive perception 16

Languages Common

Challenge 1/4 (50 XP)

The Angels Need Their Kisses.  When a Little Sister kills a target or harvests from a corpse, she can drink the harvested contents.  It takes 1 minute to complete this.  Upon doing so, she gains resistance to all damage for 1 minute afterwards.  She also regains her health this way.


Hypo Needle.  Melee Weapon Attack: +5 to hit, reach 5 ft., one target.  Hit: 8 (1d10+3) piercing damage.

Image Sources: BioShock concept art and screenshots – Irrational Games/2K Games

Made by Doctor Necrotic, for Doctor Necrotic Media.


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