I started to work on Damage Smearing but couldn't get my head around it. I think reducing the value to 0 is going to reduce the value on the return to 0 as well.
So I'm building a few effects to get this to work.
Two timed effects, one similar to burning and another just to set the buff itself (which really does nothing except to say it's active).
Then the onHit function will split the damage in half and put half into the timed effect, which will then split the damage in half again (as it feeds back into itself), right up until the duration runs out on the Buff, when the remaining ticks will go off evenly.
At least, that's how I'm hoping it will work

*edit* Okay Damage Smearing I'm pretty happy with. The numbers don't quite add up but the effect is pretty powerful for a generic spell so if the character takes an extra 10% damage to have the damage spread out over several rounds so be it. The combat log is going to be lying big time though. Probably a worse offender then Time Prison because at least in that case you know the damage you're actually taking (0).