How do you create a Water Shield Spell (WoW Spell)

[excis]

Hi, How would you create the spell Water Shield from WoW. Basically it is a buff you can only cast on yourself that has 3 charges and increases mana regen plus every attack done on you gives you some mana and removes 1 charge. http://www.wowhead.com/?spell=52127

 

[Dirac]

Would be easy to do in MPI, for instance
Trigger 1
E - Unit starts the effect of an ability
C - ability being cast equal to water shield
A - Set Water[Player number of owner of triggering unit] = 3

Trigger 2 (Mana regen depending on charges)
E - Every 0.1 seconds
C - none
A - Loop from 1 to 12 (Integer A)
If Water[Integer A] greater than 0
Then set mana of unit to + (water)x(0.5)

Trigger 3 (use damage detection)
E - Unit takes damage
C - Unit has buff (Water shield)
A - Set water[player number of damaged unit] to: water - 1
then remove if water equal to 0

 

[excis]

What variable is Water and how do you get it to be Set Water[Player number of owner of triggering unit] = 3?

 

[BlueMirage]

It's an Integer with an Array.