Health down/up seem to work by retaining the % HP that a character has. E.g. Chewie with health up gains, say 30% max hp to 130% of his original. When the effect ends, it retains the current health percentage and drops the max health back to the original value.
From my observations, Health down works similarly. The percentage health remains the same, but the max health decreases. So what effectively happens, is that if you take any damage while the health down effect is on, take 20% health down for example, it effectively multiplies that damage by (1/(1-0.2)) = 1.25 once the effect wears off. Unless of course, any heals are rendered which work similarly.
As an illustration, take a 10k health toon that gets slapped with health down of 20%:
1. 10,000 max hp gets reduced to 8,000 max hp
2. This toon now takes 2000 damage. Current hp is 6000/8000 or 75% of max health.
3. The health down effect wears off and the max hp returns to 10,000.
4. Retaining the percentage hp of 75%, current hp is now 7,500.
5. Effective damage is 2,500 as opposed to 2,000, or 25% increase.
Currently, unsure whether Health Down across the board is a fixed percentage. I believe FOTP and GG can both apply it. Am currently doing some tests to try and determine the actual %.
