Blood Pools

This is a system for:

  • modeling how characters become better at fighting monsters they have repeatedly fought
  • providing a systemneutral orthogonal advancement track

What Blood Pools Do

Our fighter Severus is fighting four kobolds:

  • He’s fought them many times before.
  • He’s still level 1 (treasure for XP; so his previous fights against the kobolds haven’t leveled him)

Whereas a normal level 1 fighter might be a in bad way surrounded by the monsters, Severus has a Blood Pool of 3 vs kobolds.

That means he has three Kobold Blood Points to spend during the fight, which represent his experience against them.

Spend Blood Points to modify rolls.

That’s saves, attacks, damage rolls, whatever.

The default setting is for spending a BP to mean the die is rerolled, and you take whichever of the results you prefer, and you can spend as many BP per roll as you wish.

There are obvious ways to customize this system; see the Dials heading below.

Why Use Blood Pools

  • Because your characters advance slowly
  • Because you don’t use advancement
  • Because you want to model progressive experience against particular monsters

Why Not Use Blood Pools

  • Makes PCs more powerful than otherwise
  • Something else to track (but only players need to do so)

How to Track Pools & Points

Note: the “Total” Blood Pool Points are your General Pool; they mean the same thing in the text below.

How Blood Pools Work

  1. When initiative is rolled, players note how many Blood Points they have to spend this fight. Their General Blood Points can be spent vs any opponent; the Blood Points from Blood Pools associated with particular monsters can only be spent against monsters of that type.
  2. During battle, players keep track of how much damage they deal and receive vs each type of monster
  3. After battle, we see the blood pooling: take a moment to imagine the scene and describe it briefly to the players; this also indicates we are entering the phase of totaling up our Blood Pools
  4. Sum up per monster type how much damage, total, was dealt and received
  5. Split by the number of combatants in the PC party
  6. Have each player scratch that down, per monster type and the overall total
  7. Have each player multiply that number by the Blood Pool Multiplier of his class
  8. The Blood Pool Multiplier is the size of the class’s HD (by default, see the Dials section). So a 5e d10 HD fighter has a Blood Pool Multiplier of 10.
  9. Have each player add the Blood Points gained this fight per monster type to the Blood Pool entries on his character sheet.
  10. Have each player add the Blood Points gained this fight, total, across all monster types, to his General Blood Pool.
  11. If this breaks the Blood Pool Limit for an entry, the Blood Pool increases by 1 for that monster entry and its Blood Pool Limit doubles. Repeat if the current total breaks the limit again.
  12. The Initial Blood Pool Limit for a monster entry is its max hp (by default; see Dials). So a 5e goblin would have a starting BPL of 7.
  13. The Initial Blood Pool Limit for the General Blood Pool is 100 (by default; see Dials).

Appendix: Dials

These are things you can adjust easily.

  • Type of Modifier: reroll n (default), +n
  • Ratio of Modifier: 1:1 (default), 1:3
  • Point Basis: hp (default), hd, hits
  • Blood Point Totals: averaged among party members like XP (default), only what you deal and take gets added to your totals
  • Blood Pool Multiplier: full HD size (default), half HD, none
  • BP Spend Limit: spend as many BP per roll as you want (default), n per roll
  • Pool Limits: 100 for total and max hp per monster entry doubling each limit break (default), fixed numbers, limits pegged to XP thresholds
  • Monster Taxonomy Granularity: wing it (default), exact name, by type (e.g., fire elementals vs fire creatures)
  • Monster Blood Pools: monsters do not use (default), hero monsters only, all monsters

Appendix: Dissassociated?

I would say this is not disassociated since it clearly represents and has a causal link to established diagetic events.


  1. I dig this for a B/X game where you want to keep the reward for fighting low (to disincentivize it generally) but still allow pcs to get something out of it if/when it does happen. I bolt it on to fighters specifically, and just keep it as their special thing, since they generally get short shrift as B/X games advance (unless you’re using the Companion and/or Master rules).

    And yeah, the podcast version came across much clearer than reading this. Maybe it was the inclusion of examples.

    Liked by 1 person

  2. I love this. i’ve been wanting to switch over to LotFP(or old school xp requirements at least) for my next campaign and this would be a nice incentive to players who feel they are leveling too slowly.

    Liked by 1 person

  3. On the subject of disassociation… I definitely agree with you that this is a pretty easy thing to consider diagetic in some sense (even if it’s more numerically precise than the characters would consider it). I’ve been thinking about XP in old-school games recently though – particularly treasure for XP… and I think I’ve come to the conclusion that it (unlike this) is pretty much a completely disassociated mechanic. Which is OK, it still serves to create the gameplay experience it’s supposed to – I just don’t think I’d ever thought of it in such stark terms before.

    Liked by 1 person

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