Custom Raise Dead Ability

I wanted to make a custom version of raise dead for one of the heros in my campaign. Here is how i want it to work:

At lower levels the hero needs more then one corpse to raise one unit, because the necromancer is not very good at it yet. and it would scale down using less corpses at each level while the unit gets better and lasts longer at each level.

I was wondering if there was a way with triggers to do this? i havent done anything to complex with triggers yet but i couldnt find a way to do it. If anyone could help it would be great.

You would have to make a dummy spell for the casting itself. This one should have cooldowns, mana costs and such.

For the summoning, create a spell based off feral spirit that just summons an undead creature, with no cooldown or mana cost.

Have it run a trigger that looks something like this:

Event:
An unit starts the effect of an ability

Condition:
Ability being cast equal to [Your dummy ability]

Actions:
If ability level of (your dummy ability) for (Casting unit) = 1
Set [number of corpses required] = [number required for level 1]
else
If ability level of (your dummy ability) for (Casting unit) = 2
Set [number of corpses required] = [number required for level 2]
else
...etc, for each level of the spell.

if (number of units within [Range to look for corpses] of (Casting unit) matching conditions: (Matching unit is Dead) greater than or equal to [number of corpses required] then:

For 1 to [number of corpses required] do (Remove (Random unit from (Units within [Range to look for corpses] of (Casting unit) matching conditions: (Matching unit is Dead)) from the game)
Create 1 InvisibleCasterUnitWithTheSummoningSpell for Owner of (casting unit) at position of (Casting unit)
<Give the created unit an expiration timer of a second or two, as well as the Aloc ability.>
Order last created unit to (Orc Far Seer: Feral Spirit)

else
<Display an error message, give mana refund to caster>


I'm sure someone else can give a better explanation if you can't get this to work.

thanks for the help. Ill give that a try although it seems like if will work from reading it. If i have any problems ill let you know