[Trigger] Critical Spells and Buff

[lnfernal]

I need a little help with my map about critical hits. I was thinking of making that every unit/hero in my map to have 2% chance to crit, but this ability would of course be hided so I decided to but it in a spellbook and hide it.

First Question. Critical Spells and Varies Damage.
But I want this critical to both affect Spells and Melee, and the critical damage is between 2x to 2.5x. But I got no clue how to make critical for spells or the damage multipler varies. Can you give me some suggestion or even make a trigger for me?

Second Question. Critical Buff
Is it possible to make a kind of critical buff? Like:

Event
A unit is attacked
Condition
Attacking unit has a buff equal to Critical Buff
Action
Add Critical Hided Varies Damage Skill to Attacking Unit
Wait 10 seconds
Remove Buff from Attacking Unit

 

[Volvox]

Such things have to be MUI, i advise using JASS here, triggers will cause major memory leaks and will get bugged very often.