Made by request (
http://forums.rpgmakerweb.com/index.php?/topic/47564-poison-damgage-based-on-attack-rather-than-percentage/).

This plugins allows you to setup damage formulas for you States, just as if they were skills.
For now, it supports up to four parameters that can go in the
[Note] field of any state:
<formula:FORMULA_HERE><element:ELEMENT_ID><variance:VARIANCE_PERCENT><heal>Substitute FORMULA_HERE for a damage formula, in the exact same format you would use in the Skills entries.
Element_ID should contain the number of an Element (Types). It defaults to 1 if you omit it.
Variance is the % of variance in the damage. It defaults to 0 if you omit it.
If you put the heal tag, the skill will heal instead of dealing damage.
Creating this was surprisingly insightful, and I kinda of purposefully avoided the easy way out of this one (having the Maker create a Skill and reference that skill via the state notes, for it to be applied every turn; I think that feels too clunky when navigating the database).
And I'm pretty sure that the way I used to display damage numbers is not the correct way to do it. So I'll very likely come back to update and polish this plugin in the future. I already know some parameters that I want to add to it, later.
Do let me known of any bugs (or any major incompatibility) that this one might have.
Legal:
Free for any kind of use.
I don't give any warranty.
* Version: 2015-11-20-2232
*
* CHANGE LOG:
* 2015-11-20-2232 - Normal attack states should also get the caster paramaters properly now.
* 2015-11-19-2359 - Fixed decimal damage.
* 2015-11-19-0021 - Release of Version 2 Beta - changed how the damage is applied, needs a lot of testing.
* 2015-11-08-0156 - Changed the _stateCaster array to no longer store direct object references, since that could easily result in infinite data loops. Thanks, Bobstah.
* 2015-11-05-1029 - Added tags <drain>, <mp_drain>, <mp_heal>, <mp_damage>, <can_critical>.
* 2015-11-04-2327 - Made this compatible with Yanfly's Cooldowns.
* 2015-11-03-3442 - Fixed _stateCaster information being unintentionaly shared between battlers.
* 2015-11-01-1141 - Added collapse animation for enemies that die due to status effects.
* 2015-10-31-1802 - Fixed a bug that made the plugin not work properly in many cases.
* 2015-10-31-1434 - Fixed a crash at turn end.
* 2015-10-31-1225 - Fixed a few potential crashes.
* 2015-10-31-0221 - Beta Release.
Download:
http://pastebin.com/TiJxL4xi