Creating A True Passive Mana Shield

Is there a clean way to implement a passive mana shield that:
1. Doesn't show an icon
2. Works exactly like mana shield would
3. Autoactivates itself once it's depleted while still maintaining hero orders

I know JASS, and I know it well. There are some ways I can think of doing it, but I would much rather use the actual ability Mana Shield (since it's hardcoded to already do 90% of what i need it to), thus I'd prefer that rather than building my own mana shield engine, or using a custom engine like shadow1500's.

Thanks if anyone knows anything.

Will hiding a Mana Shield ability with a spell book work?

It will still need to be reactivated if it is depleted.

Not hard, 1 trigger would do that. Event: Units mana greater than 50, action: order unit to "manashieldon"

http://www.wc3campaigns.net/showthread.php?t=80544

I think this might help you.

Yes it will, but you will have to change a few things so it uses mana instead.
Vexorian had released a passive mana shield so you might want to use that instead.