See post 1 here.
See post 2 here.
A follow-up thought I had was to try a compound XP bonus. This would simply be a matter of applying the XP bonus to your XP total each time XP are awarded, rather than only to the just-earned XP.
So it would work like this:
- Session 1: You earn 400 XP. Your XP total is 400. Apply your 10%. That gives you 440 XP.
- Session 2: You earn another 400 XP. Your new XP total is 840. Only now apply your 10% to that number (instead of to the 400 XP you just earned). That gives you 924 XP (instead of the 880 you would have had if you were applying the bonus only to the XP just earned).
- Sessions 3 and beyond: Just keep applying the 10% XP bonus to your total XP each time more XP are awarded.
Again, using the OD&D Fighter XP progression as a baseline, and assuming an increase of one level every five sessions for a character with no bonus, we'd get the chart below. I've included the numbers for "no bonus," the traditional "10% to earned xp" covered previously, and the "10% compound bonus" for comparison. The yellow cells are where a fighter would level up depending on the bonus applied. The word "lap" indicates that the character jumps a full level ahead of a no-bonus character.
What you get is the fighter with the compound bonus advances at an accelerated (perhaps too accelerated) pace relative to one without the bonus. The fighter with the compound bonus "laps" the no-bonus fighter at session 15, hitting level 5 at the same time the no-bonus fighter hits level 4. He then gradually increases his lead as he moves toward lapping the no-bonus fighter a second time at session 35. At the end of that session, the no-bonus fighter rises to level 8, while the compound-bonus fighter hits level 10.
Would the compound bonus work? For a long campaign, I think I would not want to use it. For a short to mid-length campaign, perhaps going to only level 5 or 6 or so, I think it could be an interesting way to handle the XP bonus in a meaningful way. But even then, I don't think it would be a better way than the simple, flat 25-30% bonus to earned XP from my previous posts. I think the higher flat bonus to XP earned might be the cleaner way to achieve the end I'm seeking.