A Hazard Die for Combat: Replacing Initiative and Spicing Up Combat

At the beginning of each round of combat, roll the Combat Die. Unless stated otherwise PCs go first:

Combat Die: (1d6)

1. Player Characters go first!
2. "Slow" Creatures go second, Starting with normal PCs, then normal, NPCs, then slow PCs, then slow NPCs. (Slow refers to anything wearing heavy armor, wielding large weapons, encumbered, or with reduced speed like dwarves or halflings)
3. Enemies gain a leg up! Enemy NPCs go first!
4. Ongoing effects end or allow for a Save. (The flaming patch from the firebomb goes out, the wizard's forcefield goes away, charmed PCs snap out of it, ect..)
5. Enemies call for back up! Roll a Dungeon Hazard die and only implement if it is an Encounter.(Enemies will only do this is it makes sense for them to. If you are fighting another party of adventurers, they aren't likely to have allies in the DUngone to call for. In which case, the enemies ought to change their tactics once this is rolled in some way.)
6. Environmental effect! (Dynamic environments do their thing. The earth shakes, the stars align for the ritual, flaming debris falls from the burning ceiling, ect...)

This would require the reworking of some mechanics but it does allow for some unpredictability in combat and some new design opportunities such as...

Boss Monsters can add effects to the Combat Die!

For instance, Saurfang the Dragon can whip his tail or try to hypnotize a PC off of his turn. Just upgrade the die to a d8 and add both options to the Combat Die chart.

The Arcanik Golem of Lost Tenebria has differently colored modes that effect which abilities he has. Add "Mode Switch" twice or "Red Mode" and "Blue Mode" to the chart and use a d8.

Certain Events can be happening while combat is going on that are affected by the die. 

For instance, the Cultists of Kakabad can progress in their foul rite. Add 2 "The Beast Stirs" to your Combat Die, use a d8, and after this has been rolled twice, the Cultists fell lord, the Grim Beast of Kakabad, is summoned.

I don't know how usable this is. Part of me dislikes any chart that forces itself on the game too often. Another part really likes the dynamic of this roll.

I could also see versions of this mechanic that would relate directly to abilities. Like the fighter can use Cleave again or the dragon recharges his breath weapon.

What do you think?